The work described here was carried out during the last three years mainly on the castle premises at Lužany near Přeštice (Hlávka's foundation). It dealt with the disease of the horse chestnut-tree (Aesculus hippocastanum L.). The symptoms and their development have also been observed at a number of other places. According to the classification ofBose (Wageningen) the symptoms belong to the groups of Colour changes (II), Necrosis (IV), Deformation (VII) and partly also Growth reduction (of fruits). We are dealing here with a disease that was described bySorauer andThomas 60 years ago as abiosis. Since some of the symptoms suggested a virus origin of the disease some diagnostic tests were carried out. The serological test was negative on account of the chemical composition of chestnut leaves which are not amenable to such tests. Grafting and inoculating tests on healthy seedlings were positive. Viral necrosis of the horse chestnut is a disease of the system which is not transferred by contact. It is readily transferred by grafting and inoculating. Some symptoms suggest that it can also partly be transferred by seeds.

Chromatographic analysis of wheat leaves grown for 4 to 10 days in a solution of gibberellic acid (10-20 p.p.m.) revealed a higher level of fructose-1,6-diphosphate as compared with that of 3-phosphoglyceric acid and phosphoenolpyruvic acid, and of 3-phosphoglyceric acid as compared with that of a hitherto unidentified phosphate. These changes were found under different light regimes which preceded extraction of phosphates from leaves. On the basis of these data and in view of earlier results (Luštinec, Pokorná, Růžička 1962) it is assumed that glycolysis interacts with reactions utilizing its intermediate products for the synthesis of lipids, this representing a possibility of bringing about changes in leaf phosphate levels due to gibberellic acid. In order to verify the postulate the incorporation of 1-¹⁴C- and 6-¹⁴C-glucose into lipids, phospholipids (the magnesium salts of which are insoluble in acetone), carbon dioxide and the non-lipid fraction of leaves was investigated. It appeared that the incorporation of 1-¹⁴C into the lipid fractions of plants grown for 3-7 days in a gibberellic acid solution is markedly lower than that of 6-¹⁴C. The ratio of radioactivities C₆∶C₁ was increased in the lipids by the three-hour treatment of leaves with gibberellic acid (10 and 50 p.p.m.) during their incubation with glucose-¹⁴C. In view of the fact that the amount of substances extractable with ether is the same in the experimental and in the control leaves and that the incorporation of 1-C into lipids is frequently considerably higher in the controls than the incorporation of 6-C the effect of gibberellic acid on the rate of exchange of carbon atoms between the lipids and the products of glucose catabolism should be borne in mind.

Ascorbate oxidase was studied as one of the terminal oxidases in the roots of seven-day old squash cultures (Cucurbita pepo L.) in relation to calcium nutrition and the influence of calcium deficiency on the quantity and quality. The work led to the following conclusions:
1) Ascorbate oxidase was identified inCucurbita pepo L. roots, sort "Kabačky". Identification was carried out according to substrate oxidation, and the sensitivity of enzymes to 10^-4 M DIECA; the possibility of interference by other oxidase systems was eliminated during the study of the oxidation reaction by the use of acetone preparations.
2) Dependence of the activity of enzyme on pH, temperature and concentration of the substrate was determined and the stoichiometry of the reaction (1/2 mol. O₂ per 1 mol. ascorbic acid) was verified.
3) Activity of enzymes of cultures, cultivated in a complete nutritive solution ("NS") and calcium deficient ("-Ca") solution, and changes in activity during the development of cultures, were compared. Converted into fresh weight, the activity of the "-Ca" variant is significantly higher (about twice) than that of the "NS" variant. In both cases, however, it was sufficient to cover the O₂ consuption of intact roots. Qualitative differences in enzymes of the two variants were not determined.
4) Cytochromoxidase may participate in the oxidation of ascorbic acid in the roots. Participation of polyphenoloxidase was not proved. With the intermediation of ascorbic acid, ascorbinoxidase can oxidize hydrogen-SH-groups of cysteine.
5) Addition of ascorbic acid to root tips causes a considerable rise in QO₂ (by to 90%), therefore activity of oxidation systems of ascorbic acid is not fully used in intact cells during endogenous respiration.

Bei der Sichtung meines reichen Materials von mixoploiden Wurzelspitzen habe ich Wurzeln gefunden, welche sich des polyploiden Sektors dadurch zu entledigen schienen, dass sie sich in einen diploiden und einen polyploiden Teil spalteten. Die Abspaltung von polyploiden Zellsträngen kommt zwar häufig vor, in den hier beschriebenen Fällen bildet jedoch der diploide Sektor eine neue Wurzelspitze, der polyploide Teil stellt allmählich sein Wachstum ein, während die neu differenzierte Wurzelspitze weiter wächst. Auch das ist eine Art von Bereinigung und Diploidisierung der mixoploiden Wurzelspitze. Sie setzt allerdings voraus, dass die Wurzelspitze etwa zu einer Hälfte meist aus diploiden, zur anderen meist aus polyploiden Zellen besteht. Es findet dann im Urmeristem der diploiden Hälfte eine Umdifferenzierung zur selbständigen Spitze statt, wogegen der polyploide Spitzenteil allmählich oder plötzlich die Teilung seiner Zellen einstellt, sodann sich eine Zeitlang streckt, dann aber zerrissen wird und abstirbt. Ich konnte einige solche Fälle schon in ihren anfänglichen Stadien beobachten. Der Vorgang ist nicht auf den eutelischen Typus beschränkt.

The previously found (Slavík, 1959) distribution pattern of osmotic pressure of cell sap in the area of the leaf blade of dicotyledonous type which is independent of the water balance and unchanged even with zero diffusion pressure deficit, was complemented by further data concerning the physiological heterogeneity of the adult leaf blade ofNicotiana sanderae hort. in relation to water relations and CO₂ exchange.
The transpiration rate from the intact leaf surface was found to be about 50 to 70 per cent lower in the apical part of the blade than in the basal part. The natural permanent water saturation deficit was found to be about 10 per cent lower in the apical part. The stomata density in tobacco as well as in sugar beet leaves were on an average 40 per cent lower in the apical part, their size being here 30 per cent higher. The relative index of the area of the stomata pores (density × square of the pore length) did not differ significantly in the two places. The photosynthetic rate (per area) in fully water saturated leaves was found to be 17 per cent lower in the apical part of the blade, the chlorophyll content (per unit area) being greater in the thicker apical part. Respiration rate measured manometrically as Q_O2 was significantly lower in the apical part, both when calculated according to area and to dry weight (12 per cent). Similar but much lower differences were found between the edge and the central part of the leaf blade.
This physiological heterogeneity and polarity of the leaf blade originating in the ontogenesis of its extension growth is causally based on the different relative hydration levels. Thus the study of various physiological processes in different parts of the leaf blade is suitable for the investigation of their relationship to different hydration levels.

Changes in the osmotic potential of the cell sap in passive water balance (wilting) of parts of the leaf blade were determined in relation to increasing water saturation deficit. Theoretically it could be assumed that the water lost in passive water balance comes from the total cell water equally, hence also from an aliquot part from the water contained in the cell sap. In that case the concentration of the cell sap would increase in proportion to the growing water saturation deficit. In the absolute majority of investigated cases, the osmotic pressure increased (the osmotic potential fell) more steeply than corresponded theoretically to the loss of water at the time. From the difference observed between the mentioned theoretical course and the values found, an estimate of the percentage of "mobile" water in the cell, i.e. that part which was always directly involved in changes in the water content in the cell, was calculated. This "mobile" water in adult leaves constituted about 70 to 80 per cent. The proportion of "mobile" water was dependent on the rate of development of the water saturation deficit: When the wilting was rapid the amount observed in adult leaves was smaller than in the case of slow wilting. This proved that the "mobile" proportion of the cell water is determined according to the water balance by a dynamic equilibrium of intracellular diffusion currents of water according to gradients of the potential between the different parts of cell water which are determined by different linkage ("bound" water) as well as different localization in the cell.

1. Humussäure (Humussäure Riedel-de Haen A. G. Seelze-Hannover als K-Salz) stimulierte im Dunkeln genau so wie im Lichte am stärksten die Entwicklung von Frischgewicht, Trockensubstanz und die Länge der oberirdischen Pflanzenteile bei Weizen in Kulturen mit destilliertem Wasser. Die Wachstumsstimulierung war hier so wie im Lichte mit einem signifikant niedrigeren Spiegel der einzelnen freien Zucker verbunden.
2. Im Dunkeln wurde jedoch keine signifikante Stimulierung des Wurzel-wachstums unter dem Einfluss von Humussäure festgestellt, wie es im Lichte der Fall war. Ebensowenig wurde in der Erstblattphase eine hohe Ansammlung von freien Zuckern in den Wurzeln bei der Variante Humussäre-destilliertes Wasser beobachtet, wie es im Lichte der Fall war. Der Zuckerspiegel war hier sogar niedriger als in den oberiridischen Pflanzenteilen.
3. Die Anwesenheit von Mineralnährstoffen in den Kulturen nahm bei beiden Pflanzenteilen der stimulierenden Einwirkung der Humussäure auf das Wachstum die Wirkung wie bei den Versuchen im Lichte. Ähnlich verhielt sich der Zuckerspiegel. Die Anwesenheit von Humussäure in der Nährlösung war mit einem niedrigeren Zuckerspiegel verbunden; stark beweiskräftige Unterschiede bestanden aber nur zwischen Pflanzen der Varianten mit destilliertem Wasser. Bei Wurzeln im Dunkeln stellten wir eine höhere Maltosemenge im Vergleiche mit Wurzeln aus Lichtversuchen fest.
4. Der Einfluss des Lichtes auf die oberirdischen Pflanzenteile und die Wurzeln im Zusammenhange mit Wachstum, Pflanzenstoffwechsel und dem Einfluss der Humussäure wird diskutiert.
5. Zusammenfassend kann gesagt werden, dass die Reaktion der Wurzeln auf die Einwirkung von Humussäure in bezug auf Wachstum sowie die Spiegel der einzelnen Zucker wie im Lichte deutliche Unterschiede zeigt. Die Mitwirkung der photosynthetischen Vorgänge in den Blättern bei der Beeinflussung der physiologischen Vorgänge in den Wurzeln durch Humussäure ist zu erwägen.

The effect of photoperiodic inhibition on the course of development was demonstrated by changes in the length of the sheath and the lamina, the lamina being more affected than the sheath. In a number of variants with different initiation of photoperiodic inhibition, an elongation or shortening of the sheath and the lamina of the three top leaves was observed compared with corresponding control leaves. The shortening occurred in leaves which developed beyond the normal number of the original bracts. This was the case with variants with very early inhibitions. Variants with later inhibition had on the one hand abnormally reduced leaves with imperfectly developed spikes, on the other hand elongated leaves whose length resembled that of ontogenetically younger, lower leaves. The suitability of the morphology of leaves for the investigation of the course of plant development is discussed.

Decapitated seedlings ofLinum andPisum treated with TIBA paste either above or below the cotyledons, showed different morphogenetic changes especially on the epicotyl stumps, due to the differences in the correlations of their epigeous and hypogeous cotyledons respectively, these being also primarily responsible for the differing dominance of their shoot primordia.
At the earliest phases of germination, an antagonism between TIBA and IAA can be demonstrated on the first internode inLinum, which is usually very short, as well as on the petioles of thePisum cotyledons. The former could be enlarged only by treatingLinum seeds, even when ripening on the plant, with TIBA paste and the latter, if retained by soaking seeds ofPisum in a TIBA solution could be promoted by exogenous IAA. This, on the contrary, reversed the morphogenetic effects of TIBA uponLinum seeds.

1. A method of "measuring strips" for the investigation of the sap exudation of crops under field conditions is described. The quantity of liquid exuded from the detopped stem stump is determined from the length of a wetted zone of a narrow strip of filter paper protected against evaporation of the liquid by a polyethylene cover bag. The strips with the cover bags can be used even to collect greater amounts of exudated liquid.
2. Using this method, the sap exudation of detopped maize plants was observed during the whole growing season. On typical curves illustrating the course of the wetting of the measuring strips, the temporary absorption of the sap from the cells and conducting elements severed by the cut, the lag in exudation and the actual sap exudation can be distinguished.
3. The length of the lag period indicates the magnitude of the momentary water deficit of the investigated plant and the rate of sap exudation indicates the availability of soil moisture.
4. The rate of sap exudation reached its maximum at the end of June and then decreased gradually. In this period also the distinct lag periods were first observed. The occurence of shorter lag periods between the 5th and 29th July, i.e. in the shooting stage which from the standpoint of precipitation is critical for the height of yield, signifies that the critical stage probably coincides with the period in which the natural disproportion between available soil moisture and transpiration may become important.
5. During the period of long lags towards the end of the growing season, the measuring strips were fastened upon the plant stumps 24 hours after the decapitation. The "exudation after 24 hours" determined in this way indicates a significant decrease at the end of August when the soil moisture dropped to a value approaching the permanent wilting percentage.
6. The results have shown that the method of "measuring strips" permits an easy and sensitive evaluation of the water relations of maize plants growing under field conditions.

From the roots ofCucurbita pepo L. an acetone preparation was obtained with a polyphenol-oxidase activity towards pyrogallol, less marked towards pyrocatechin and DOPA. It is competitively inhibited by DIECA and KCN, but is not indibited by NaN₃, which is evidence that it is a copper enzyme of the polyphenol oxidase type. No quantitative differences between the two variants "NS" and "-Ca" were found nor qualitative differences expressed by the affinity for the substrate.

Die Ergebnisse der beschriebenen Versuche weisen darauf hin, dass in jungen Vegetationskegeln von Weizenpflanzen (2. Etappe der Organogenese), die aerobe Gärung eine wichtige Rolle spielt, während in älteren Vegetationskegeln die aeroben Oxydasensysteme in den Vordergrund treten. In den Vegetationskegeln werden die meisten Aminosäuren nicht in grösserer Menge synthetisiert, selbst wenn ihnen Aminostickstoff angeboten wird. Die wichtigste Quelle für die Eiweizsynthese stellen die aus den Blättern transportierten Aminosäuren dar. Die Umwandlung derselben im Vegetationskegel ist aber möglich. Dies geht nur unter aeroben Bedingungen vor sich. Die vorliegende Arbeit wird durch die direkte Messung der Aktivität einiger Enzyme ergänzt werden.

With the aim of finding a biochemical criterion of pollen fertility the pollen of diploid and triploid apple varieties was investigated for the content of the following aminoacids: alanine, γ-aminobutyric acid, aspartic acid, asparagine, arginine, cysteine/cystine, phenylalanine, glutamic acid, glutamine, histidine, leucine-isoleucine, proline, serine, threonine and valine. The apple pollen was found to contain the greatest amount of proline, the principal amide being asparagine. The pollen of diploid varieties contains more proline and less histidine as compared with that of the triploid ones. Both differences are highly significant. The proline-histidine quotient (PHQ) represents an important criterion of pollen fertility. Its value varied between 1.2 and 8.1 for seven triploid varieties, and between 17.5 and 53.3 for seven diploid ones. It depends not only on the variety but also on physiological conditions of the tree given by the environmental situation. The varieties tested do not significantly differ in the content of other amino-acids in pollen.

Sodium fluoride, iodoacetate and malonate inhibit or stimulate the respiration of wheat roots cultivated for 2-10 days in a solution of sodium humate (100 mg/l.) as compared with the respiration of roots cultivated in water. The influence of sodium fluoride on the respiration of leaves is similar. The ratio of the radioactivities of C¹⁴O₂ from glucose, labelled in the position 1 or 6 (C₆/C₁) is distinctly higher in roots, but not in leaves. The change in this ratio is accompanied by a decrease in the total radioactive C¹⁴O₂ from roots of plants influenced by humate, from glucose labelled specifically and totally.
Endogenous respiration (QO₂) of roots increased in humate by 5-30%, the intensity of leaf respiration remaining at the same level. The longitudinal root growth increased in humate by 20-80%, the growth of leaves by 5-15%. The above statements show that in a humate solution the glycolytic fraction of the respiratory metabolism of roots is increased.

The direct influence of irradiation on the production of anthocyanins in detached uncoloured petals of balsam cultivated in vitro was investigated. No qualitative changes occurred in the given case after irradiation. The quantitative content of anthocyanin shortly after irradiation also remained on the whole unchanged, nevertheless, after three weeks, a marked decrease in the quantitative content of anthocyanins occurred.

In studying the character of the relationship between the porphyrin metabolites containing iron and magnesium the catalytic activity of Fe-porphyrins and the possibility of their participation in chlorophyll formation in leaves and roots of plants was considered.
The results obtained elucidate the changes in the pigment content of leaves in the course of iron utilization by the plant (i.e. of the activity of iron-containing enzymes, synthesis of protohematin). The main trend of changes was observed in the following cases: (1) during utilization of various compounds affecting the individual components of the oxidation-reduction systems and the pigment content of the plant; (2) during changes of metabolism due to altered conditions of mineral nutrition: (3) in comparing the metabolism of variegated plants.
It is assumed that in all the cases the process of chlorophyll formation is directly associated with the processes of iron utilization by the plant both in the leaves and in the roots.
Data concerning the synthesis of protohematin in the isolated roots of some plants, on the activity of Fe-porphyrin enzymes therein and on the formation of chlorophylls during illumination of roots are presented. The question of the significance of synthesis of Fe- and Mg-containing porphyrins in roots for the metabolism of the whole plant is discussed.
The possible relationship between the processes of energy conservation or utilization by the cell and the equilibrium between the processes of pigment synthesis and catabolism in plastids are taken up.

Comparative cryoscopic determinations of osmotic pressure and the refractive index of cell sap were analyzed with the aid of correlation coefficients and characteristics of the trend of their course (by means of the slope of the regression lines and probability field). It was confirmed that an indirect estimation of the osmotic pressure of the cell sap is readily feasible refractometrically and that it is sufficiently reliable if a relationship between the two values is determined experimentally in advance. The biological homogeneity of the material tested influences this relationship, both genetic and ontogenetic. This conclusion followed from the evaluation of the correlation between osmotic pressure of cell sap and its refractive index in leaves ofHordeum sativum Jessen. The significance of biological homogeneity was brought out by the classification of all measured pairs of values into groups according to varieties and according to leaf insertion.

Proliferation of the cambium and parenchyma of branches from 34 tree species was studied by means of tissue culturesin vitro. The formation of callus tissue, the seasonal activity of cambium, the effects of indole-3-acetic acid on the reactivation of cambium and the polarity of callus formation were investigated.
Various tree species are characterized by a different capacity for callus formation; in the majority of species, however, the reaction of cambium takes place in culturesin vitro. Some species produce callus from the cortex and the pith of branches and the lenticels simultaneously with the reactivation of cambium.
Growth of callus tissue was maximal in winter, adequate in spring before budding occurred and later decreased greatly. During the summer the growth-rates increased again and in the autumn were close to those encountered during the winter. Some species are characterized by a similarly intensive cambial proliferation throughout the whole year.
Indole-3-acetic acid (IAA) in the cultivation medium had various effects on the growth of callus tissue in the species examined. A series of species initiated meristematic foci in callus tissues that gave rise to roots (more frequently on media with added IAA) or to buds and stems.
The position of the sections in the medium (whether the apical end was placed upwards or downwards) had no great effect on the polarity of callus formation. Some species produced callus tissue at both ends of sections.

1. A comparison of the immunochemical similarities in the proteins legumin and vicilin and the albumin fraction of pea seeds (Pisum sativum Poir), was carried out.
Legumin and vicilin are globulins with different physical properties, but probably with a certain degree of immunochemical similarity as shown by serological cross reactions.
Albumins from the pea seeds, on the contrary, have not only different physical properties but they also do not even show any immunochemical similarity to globulins.
2. Immunochemical specificity of legumin and vicilin in the globulin fractions of the seeds of further species of the familyViciaceae was sought: in representatives of the genusLens, Vicia, lathyrus, Pisum, Cicer, Medicago, Trifolium, Lupinus, Phaseolus andGlycine.
Legumin and vicilin more or less similar to that of peas are present in all the observed representatives of the tribeVicieae (that is in some species of the genusPisum, Lens, Vicia, Lathyrus, Cicer); in observed representatives of the tribeTrifolieae (i.e. in species of the genusMedicago andTrifolium) the only protein is similar to vicilin; in investigated species of the tribeGenisteae andPhaseoleae, proteins similar to legumin and vicilin are missing.
In all observed representatives of the tribeVicieae (Pisum sativum Poir,Lens culinaris Med.,Lathyrus clymenum L.,Lathyrus sativus L.,Lathyrus silvester L.,Lathyrus odoratus L.,Vicia faba L.,Vicia sativa L.,Cicer arietinum L.), indications of leguminoid and vicilinoid protein characters are present in varying degrees and thus even here no cases resembling loss mutation of protein characters were discovered. The following generalisations may thus be made: the tribeVicieae is characterised by the presence of leguminoid and vicilinoid proteins (or proteins rather like them): the tribeTrifolieae is characterised by the presence of proteins similar to vicilin: in the tribeGenisteae andPhaseoleae, leguminoid and vicilinoid characters are missing. Because of the similarity of proteins in the tribesVicieae andTrifolieae, closer phylogenetic relations can be assumed to exist between the tribesVicieae andTrifolieae than between the tribesVicieae andPhaseoleae orGenisteae.
3. Legumin and vicilin are at the same time examples of protein characters with a relatively wide occurrence (these protein characters rather resembling each other are present in all the representatives of the related genera and tribes studied).
4. Further it can be assumed on the basis of unequal distribution of the proteins legumin and vicilin in the related tribes investigated (vicilin has a wider occurrence), that both proteins have not developed in parallel, but that they apparently are of unequal phylogenetic age. And it may be concluded either that vicilin is relatively a more primitive protein character than legumin or that phylogenetic differentiation of legumin was relatively more rapid than such differentiation of vicilin.

Die Entwicklung der Samenanlage des Weizens (Triticum aestivum L. var.erythrospermum cv. Niva, Früjahrssorte) von der Befruchtung der Eizelle bis zur völligen Reife des Getreidekornes haben wir beobachtet. Auf Dauerpräparaten beobachteten wir die Bildung der Fruchthülle und der Samenschale. Wir konnten feststellen dass sich die Fruchthülle im erwachsenen Getreidekorn eng an die Samenschale anlegt, von der nur eine einschlägig, mit einer Kutikula bedeckte Schicht erhalten bleibt. Epidermis und Hypodermis wachsen nicht it den Querzellen zusammen, sondern trocknen nur an; man kann schwer von einem Verwachsen sprechen, wenn der Teilungsprozess sein Ende gefunden hat und dort, wo die Gewebeschichten durch eine Kutikula getrennt sind..

1. Treatment with high to sublethal doses of streptomycin (1 m Mol, 0.5 m Mol) did not induce any significant increase in chromosome aberrations at the metaphase and at the ana- and telophase. The only significant increase in aberrant ana- and telophases was observed as a consequence of treatment with 1 m Mol streptomycin (30 °C, 48 hrs recovery). This increase was mainly caused by the presence of lagging chromosomes and was therefore the result of spindle damage and not of chromosome aberrations. This fact was verified by the nonsignificance of the increase in aberrant metaphases under the same treatment. The disadvantages of evaluation of chromosome aberrations in ana- and telophase are stressed in the discussion.
2. Simultaneous treatment with low doses of streptomycin (0.005, 0.0005 m Mol) and ethanol showed a decrease in the frequency of chromosome aberrations compared with their frequency after ethanol treatment alone.
3. Pretreatment with 0.05 m Mol streptomycin for 2 hrs reduced the number of chromosome aberrations, induced by ethanol.

In the course of six years, pollination interrelations and self-pollination ability were investigated in seven more important Sour Cherry (Cerasus vulgaris Mill.) cultivars grown in Czechoslovakia. The success of pollination was evaluated according to the percentage of fully ripened fruits. A survey of results obtained is given in Table 1.
Reciprocal incompatibility was found between two cultivars (De Olivet, Brune de Bruxelles). Thus, the first incompatibility group in Sour Cherries has been established. The other varieties form combinations with different degrees of compatibility. The varieties studied are listed in Table 2 according to their general fertility and pollinating ability.
Complete autosterility was found in two cultivars (Körösi, Brune de Bruxelles), two others, on the other hand, showed a very high degree of self-fertility (Morello, Griotte de Vít). These two varieties also render the best results when intercrossed. The remaining cultivars (De Olivet, Griotte de Vacek and Ostheimer) are only very little self-fertile and need the presence of good pollinators to ensure a satisfactory crop.

1. Die Antherenlänge ist beiLilium henryi kein Massstab für das im Innern der Antheren ablaufende Stadium der Pollenmeiose und Pollenentwicklung. Es bestehen signifikante Unterschiede zwischen den Antheren-Längen gleicher cytologischer Stadien zu verschiedenen Zeitpunkten der Vegetationsperiode.
2. Durch amperometrische Titration bei 0° C in Stickstoffatmosphäre konnte in Extrakten des Tapetums und des Archespors eine zyklische Änderung im Gehalt an Thiol-Gruppen während zweier Vegetationsperioden gefunden werden. Der Sulfhydrylgehalt zeigte, bezogen auf den Stickstoffgehalt, synchrone Maxima im Pachytän und nach der Tetradenbildung.
3. Bezieht man die mg Äquivalente SH auf mm der Antherenlänge, so ergeben sich für das Archespor Maxima in der Diakinese und in der Metaphase 2, während im Tapetum Maxima des SH-Gehaltes während der Diakinese, kurz vor dem Tetradenzerfall und während der Einlagerung des Pollenfarbstoffes defunden werden. Daraus wird auf einen Transfer von SH-Gruppen aus dem Tapetum zu den Mikrosporen während der Metaphase 2 geschlossen.
4. Eine Änderung des Gehaltes an SS-Gruppen konnte während der Pollenmeiose und Pollenentwicklung nicht beobachtet werden.
5. Der grösste Teil der ermittelten Thiol-Gruppen liegt als Glutathion vor, während eine weitere SH-Verbindung, die nicht mit Cystein identisch ist, wahrscheinlich als Peptid vorliegt.
6. Auf einen meiose-induzierenden Effekt der SH-Verbindungen konnte aus vorliegenden Messungen nicht geschlossen werden.

Transpiration rates of leaf blades of irrigated and not irrigated spring wheat plants were studied in relation to the water content and growth changes in the test plants during their development. The applied irrigation stimulated the growth and slightly delayed the development of the test plants. It increased chiefly the water content and to a lesser degree the dry solid weight in the plant body. The quantitative and qualitative properties of the water content in the plant affected not only transpiration rates, but also the development of new and the dying off of old organs and tissues, especially of leaf blades. Transpiration rates in irrigated plants were markedly higher than in not irrigated plants. Mean transpiration rates of different leaf blades varied and were typical for each leaf blade. From the static aspect it was possible to express and even to explain some of the relationships and the heterogenity of the leaf blades on the same stem by the "Law of Zalensky". This involved mainly the mean values of growth characteristics and the investigated features of the water regime. On the other hand, from the dynamic viewpoint it was possible to divide the different leaf blades according to their transpiration changes into two groups. The first group includes the blades of the first to third leaf, the second group the blades of the fourth to sixth leaf and the ear. The capacity to control the water regime in the different blades is greatest at the stage of tillering, shooting and milk ripeness. During these developmental stages the marked decrease in transpiration, caused in the first place by a number of internal and not only external factors, was explained.

A method suitable for serial determinations in genetic experiments is described. Colorimetric determination of HCN (by 1-phenyl-3-methyl-5-pyra-zolone and pyridine, phenolphthalin or sodium picrate) facilitates processing of samples releasing 0.2 μg to 20 μg of HCN. Before hydrolysis of the glycoside the oil content in the seeds can be determined. Variance analysis of the cyanogenic properties of the particular seeds of two sorts of flax with an average HCN content of 0.4 and 0.9 μg shows that the differences between plants and between capsulae of the same plant can be determined.

The cytological effects of the insecticide Systox on the primary roots of Vicia faba and possible mutagenic effects on Arabidopsis thaliana have been studied. It was found that a 0.02% watery solution of Systox after a testing period of 3,6 and 9 hours under partially anaerobic conditions gives the following results:
a) no inhibition of mitosis was produced;
b) inhibition of the spindle was produced independently of the duration of action of Systox;
c) the occurrence of chromosomal aberrations increased significantly after 3 and 6 hours without restitution and after 3 hours with restitution for 24 hours. The frequency of these aberrations may depend on the isomeration of Systox in water since in older Systox solutions-where, according to data in the literature the concentration of isomer II increases-the frequency of chromosomal aberration increases significantly after 24 hours restitution. This influence of isomeration, was not found to affect the inhibition of the spindle, mentioned above.
Partial anaerobiosis itself produces a significant increase in inhibition of mitosis after 6 and 9 hours, an inhibition of spindle formation and an increased occurrence of chromosomal aberrations as against 3 hours testing.
After the action of a 0.2% and 1% concentration of Systox for 6,48 and 72 hours on seeds of Arabidopsis thaliana no chlorophyll or other mutations in the M₁ and M₂ generation were found.

Für die Versuche haben wir Rhizone der Ackerquecke (Agropyrum repens L.) und die Frühjahrsweizensorte Niva verwendet. Die Versuchskulturen haben wir in Sand in Mitscherlichgefässen und in Komposterde im Garten durchgeführt. Die gemeinsame Wachstumdauer von Quecke und Weizen erstreckte sich im ganzen auf rund 30 Tage. Es wurde das Wachstum von Quecke, sowie Wachstumsintensität und Zuckergehalt der oberirdischen Teile der Weizenpflanzen festgestellt.
Die Versuchsergebnise zeigten, dass das Wachstum der Weizenpflanzen umso tiefer absank, je intensiver die Quecke in den Kulturgefässen anwuchs und ebenso sank der Wassergehalt der oberirdischen Weizenteile; auch der Glyzidegehalt erlitt kenntliche Veränderungen. Die Atmungsintensität stieg bei Anwesenheit kleiner Queckenmengen in den Gefässen grösstenteils etwas, während sie in Gegenwart grösserer Queckenmengen ein wenig absank. Im Vergleich zum Wachstum erschien sie aber sehr wenig beeinflusst. Hieraus geht hervor, dass die Produktivität der Atmungsprozesse unter dem Einfluss von Quecke stark herabgesetzt erscheint. Um diese Veränderungen gründlicher zu klären, ist ihr weiteres Studium von nöten.

When small branches of different plants were dipped after cutting into a solution of humic acid, a brown substance penetrated into vessels and coagulated there. The vascular bundles were stained to the height of 1-6 cm after a week. The presence of the humic acid in the parenchymal cells could not be demonstrated directly, but cells with a yellow or brown cell wall remained alive (they could be plasmolysed).
Humic acid, labelled with C¹⁴ was distributed in the same way in sterile and in non-sterile plant cultures, mainly through vascular bundles.