Pea seeds were subjected to 1; 5 and 20 krad doses of⁶⁰Co γ-raýs. The irradiated seeds were planted in damp sand and in Petri vessels. After 10-daý vegetation at room temperature and under natural light conditions the content of the following components was determined in ýoung plants: free thiamine and thiamine pýrophosphate and drý substance.
It was found that 1 krad dose stimulates the growth of the plant and increases the crop of its green parts. The doses within the range of 1-5 krads do not affect the production of thiamine. The content of the latter, particularlý in its free form, increases markedlý for the dose of 20 krads. However, such doses hamper the vegetation.
In conclusion it seems that doses of the order of 1 krad lead to positive results in respect to the growth of the plants, however, neither thiamine biosýnthesis nor its phosphorýlation is stimulated under these conditions.

The author of this paper has attempted to clarify some problems concerning the nomenclature of Golgi apparatus and Golgi zone. The actual aim of this paper is to summarize - while using the more safe nomenclature-the existing knowledge about the functional relations between nucleus and cytoplasm arising from the study of the juxtanuclear zone by electron microscopy. Some observations lead to the assumption that the juxtanuclear zone is the place where cell components are formed or transformed. Considering its temporary character in proliferating cells and taking into account the connections with endoplasmic reticulum and the presence of pores, the nuclear membrane remains apparently a barrier restraining the spontaneous movement of substances and of cell components respectively between cytoplasm and karyoplasm that can be seen e.g. in the grouping of cytoplasmic formations in the juxtanuclear zone. In plant cells, within the zone mentioned agglomerations of different cell formations have been found, either the Golgi apparatus or mitochondria, secretion granules, lipid inclusions, vacuoles or plastids. Such a gathering of cytoplasmic material has been observed especially in young embryonic cells or in cells with retarded or stopped metabolism. The older and/or intensively active cells would then absolve an expansion of the cytoplasmic material into the whole cell. Similar formative mechanisms, now available for study during some ontogenic phases or at definite functional states only, could be effective even in the course of phylogenesis. From this point of view some of the formations described could be regarded as a kind of atavisms.

The cotyledonary petioles inPisum sativum developing at the start of germination, as well as the cotylaries growing out after decapitation of thePisuin seedlings manifest very often the so-called lateral correlations, since one of them suppresses the opposite primordium when the growth inhibition in the plant coinciding apparently with the growth promotion results necessarily in a normal development only of one of these originally equal primordia. These correlations also seem to be mediated by auxin, being induced by gravity or by corresponding cotyledon and root products, which can be supported by the use of exogenous auxins.

Obwohl auf Grund vieler Untersuchungen vermutet werden konnte, daß die sog. Kakteen-Eiweißspindeln, d. h. die ZelleinschlÜsse des Kakteen-X-Virus (CaXV), aus zahlreichen verlängerten Partikeln des OaXV zusammengesetzt sind, war das dennoch bis jetzt noch nicht bewiesen. Deshalb versuchten wir im Laufe dieser Untersuchungen mittels der fluoreszierenden Antikörper festzustellen, ob die Eiweißspindeln wirklich Aggregate von Viruspartikeln darstellen.
Bei dieser Untersuchung wurde die sog. indirekte Methode angewandt. Dabei haben wir zuerst die spindelhaltigen Zellen mit dem durch Immunisierung der Kaninchen hergestellten homologen Serum gegen CaXV behandelt, und erst nachher dieselben Zellen in eine Lösung von fluoreszierenden Antikörpern gegen das Kaninohen-γ-Globulin eingelegt. Nach dieser Behandlung leuchteten die Eiweißspindeln im Fluoreszenzmikroskop kräftig gelbrÜn (Fluoresce-inisiothiocyanat). Diese Fluoreszenz bewies uns, daß die positive Reaktion eingetreten ist und daß die Eiweißspindeln aus Viruspartikeln aufgebaut sind. Mehrere Kontrollversuche haben die Genauigkeit unserer Grundversuche bestätigt.

The activity of 1-methyl-1-nitrosourea (MNH), 1-ethyl-1-nitrosourea (ENH), 1-methyl-3-nitro-1-nitrosoguanidine (MNG) and 1-ethyl-3-nitro-1-nitrosoguanidine (ENG) was tested on seeds of barley andArabidopsis. The activity of nitrosoamides tested was expressed by the germination and M₁ seedling height reduction of barley and M₁ root length reduction ofArabidopsis.
1) After the action of both nitrosoureas (MNH and ENH) the germination of barley is at the same level as that of controls, even at concentrations, leading to a maximal reduction in the height of seedlings. After the action of both nitrosoguanidines (MNG and ENG) germination decreases in parallel with the decreasing seedling height. InArabidopsis no such differences in the relation germination to root length reduction were observed after nitrosoureas and nitrosoguanidines treatment. The differences in the M₁ generation of barley andArabidopsis after nitrosoguanidines treatment may be the reason for the non-mutagenic action of MNG and ENG in barley.
2) All 4 tested nitrosoamides are active between pH 3 and pH 6 and almost entirely ineffective at pH 7 and in basic solutions.
3) The effectiveness (in relation to M₁ seedling height reduction) of the tested nitrosoamides with a methyl group (MNG and MNH) is higher than of the nitrosoamides with an ethyl group (ENG and ENH).
4) 50% decomposition of aqueous solutions (at 25° C) of MNH and ENH takes about 60 hours, for MNG 120 hours and for ENG 420 hours.
5) Aeration during treatment or a period in the cold (5° C) after treatment improved the germination of MNG treated seeds. Sucrose, KNO₃ and thiourea had no effect.

1. Kinetin at a supra-optimal dose of 1.0 mg/l reduces the growth inhibitory effect of CCC at 5 × 10^-2 M on tobacco callus and increases it on tobacco crown-gall.
2. CCC increases the content of total, acid soluble, protein anti nucleic acid nitrogm in both tissues. Kinetin partially reduces the effects of CCC on nitrogem metabolism in callus tissue, and increases it in crown-gall.
3. It is suggested that (1) CCC affects the synthesis of RNA directing the synthesis of protein, and (2) interaction of kinetin with CCC realizes via the genetic apparatus of the cell.

The enzymatic transamination reactions between aspartic and α-ketoglutaric acid and between aspartic and pyruvic acid were studied in fresh dialysed extracts of young wheat plants cultivated under various trophical conditions, in mineral solution (Knop), in the solution of an soil organic substance (potassium humate) and without nutrients (H₂O). Simultaneously, the level of endogenic aspartic acid, glutamic acid and the growth values were determined. The enzymatic reactions were characterized by determining the optimum pH, the time course, and the effect of coenzyme and of inhibitors.
The activity of the aspartate-glutamate transaminase from the root system of plants was considerably higher than the activity of the overground organs. The enzymatic activity from both parts of the plant was inversely proportional to the growth rate: intensive growth of the plants from the Knop variant was connected with their low enzymatic activity; the level of endogenic glutamic acid was high. The slow growth of the plants without nutrients was connected with a higher enzymatic activity; the level of endogenic glutamic acid was low. The plants from the potassium humate variant had an intermediate position between these two variants from the point of view of growth as well as from that of enzymatic activity. The plants with insufficient nutrition (slow growth, low level of endogenic glutamic acid) apparently have a low capacity for supplementing the glutamic acid deficit, which is essential for the metabolic processes, by increasing the activity of the reactions leading to glutamic acid synthesis (Asp-Glu) and, on the other hand, by decreasing the reactions utilizing it (Glu-Ala). For wheat plants the active aspartate-glutamate reaction is obviously physiologically more important than the direct reaction glutamate-aspartate and the reaction aspartate-alanine which in all cases had a very low activity.

The cytological analysis of 25 Yugoslav rye populations, collected from Slovenia Serbia and Macedonia, showed the presence of B chromosomes in the all populations analysed (100%). The number of B chromosomes present was small, from 1 to 3, while the average number per plant ranged from 0-13 to 0.97. The frequency of rye plants with B chromosomes for Yugoslavia had an average of 27.10%. The frequency of plants with B chromosomes and the average number of that chromosome category per plant were appreciably greater in the arid region of Macedonia than in the humid region of Slovenia, the differences being significant and real biometrically.
Comparing the data of other authors for primitive Asian rye populations, it was established that the B chromosome frequency is lowest in the populations from regions designed as centres of the origin of this plant species (Near East, Asia Minor), with a considerable successive increase of their frequency further as well toward the East (Transbaikal, Korea), as toward the West (Balkan Peninsula, Yugoslavia). Possible causes of the B chromosome frequency increase in the populations out of the centres of rye origin were discussed, and it was pointed out to the importance of their study in primitive West European populations.

U odr. Blenheimská reneta se postřiky α-naftyloctové kyseliny na letorosty strormů bez plodů neprojevily vyšším počtem založených květních pupenů. Autor proto dospěl k názoru, že otázka přímého zapojení a přímého vlivu α-naftyloctové kyseliny na zakládání kvétních pupenů u jabloné je sporná.

The applicability of the microrelief (or reprint) method for stomatal aperture determinations was studied in middle-aged sugar beet leaves. It was found that the picture of the central aperture (CA) of stomata on the reprints could be observed only if their eisoiial aperture (EA) was sufficiently wide. If the width of EA was small (about 1-3 μ), it was impossible to determine the width of CA by means of the reprint method, in view of the proportional dimensions of the upper closing flaps. A lower concentration of the chlorophorm solution of methylmethacrylate used for taking reprints had a favourable influence on the amount of stomata whose width of central aperture was reproduced on the reprints. Simultaneous measurements of the EA-width and of the diffusibility of leaves (determined porometrically) in the course of a day showed, on the whole, fairly corresponding changes. During the wilting of detached leaves their diffusibility fell to zero, where it remained. The width of EA also decreased at first, but at higher water deficits it partly again increased.

A method of calculation for determining the total transpiration (consumption of water for transpiration) of a single woody plant seedling or of their growth during periods of different length (from one day up to the whole vegetative season) is described and critically evaluated; the calculation is performed according to single transpiration intensity measuring results, by the cut-shoot method and weighing at 8, 11, 14 and 17 hours (or more often during the day).

A study of the effect of exogenous sugars (fructose, glucose, arabinose and xylose) on Qo₂ inChioreila pyrenoidosa (A 82) and inScenedesmus obliquus (A 125) showed that the effect of sugars on respiration depends on previous cultivation of the alga. In autotrophically cultivated algae all sugars contribute to the increase of Qo₂, in those cultivated rnixotrophically (with the addition of glucose or together with yeast extract, and with xylose) this occurs only in Scenedesmus when glucose or xylose are applied. The effect of cultivation was apparent in that mixotrophically cultivated algae had larger endogenous reserves of substrates than the autotrophic ones. The exogenous substrate is not preferentially respired and does not affect respiration solely as its substrate. In Chlorella, the effect of different cultivation conditions is more pronounced, the QO₂ being usually higher than inScenedesmes.

Measurements of the size of the nuclei of dioecious plants showed that the nuclei of male and female plants differ in agreement with the larger quantity of chromatin. The male. plants ofRumex acetosella andMelandrium album had larger nuclei, their Y chromosome being larger than the X chromosome, the same is true forRumex acetosa where the Y chromosome is smaller but there are two in the set.Ginkgo biloba had larger female nuclei because the Y chromosome was smaller than the X. The curves obtained by grouping all the nuclei of both sexes never had two peaks with regard to the small differences between the classes of maximum frequency.

In dieser Arbeit wurde die Wirkung von 55 Verbindungen der Pyridinreihe in der Konzentration 10^-3 m geprüft. Bei diesen Untersuchungen wurde die Grundgruppierung. die der Träger der Phytotoxizität ist, gefunden. Es wird die abhängigkeit dieser Wirkung von der Konstitution der Substanzen solehen Typus diskutiert. Verbindungen vom Typus VII verursachen eine Wachstumshemmung der Hypokotylen und besonders eine sehr starke Hemmwirkung des Wurzelwachstums, die meistens mit Chlorose verbunden ist. Zu den wirksamsten gehört 3-Styrylpyridin und manche seiner Salze. Eine starke Hemmwirkung auf das Wachstum ohne Chlorose verursachten diese Verbindungen auch beiCucumis sativus.

The content of endogenous gibberellins was determined chromatographically in the roots 14-17 days old pea seedlings cultivated in water cultures in the dark. When the epicotyls are amputated from these plants, the content of endogenous gibberellins increases significantly within 6-12 hours after amputation as compared with the intact controls, then it falls off again considerably up to 24 hours after amputation. The initial increase of the gibberellin level in the roots can be explained by transport inhibition of the endogenous gibberellins from the root to the epicotyl, the later decrease of this level to be interpreted as inhibition of auxin transport from the epicotyl into the root. This is supported by the observation that spreading of a 0.5% paste with IAA over the epicotyl stump immediately after amputation prevents the mentioned decrease of the gibberellin level in the roots, whereas this decrease is intensified by using a paste with TIBA which inhibits the auxin transport. The results of this work support the possibility of direct gibberellin synthesis in the roots.

The paper deals with the relationship between the glucose utilization and growth ofPenicillium frequentans. The vegetative growth was scanty and sporulation started at a time when glucose was abundant in the culture medium. Occurrence of autolysis in spite of the presence of glucose in the culture medium is a peculiar phenomenon reported here. The autolysing culture gives rise to conditions which favour the germination of spores and the development of vegetative growth. The citric acid is the major metabolite produced by the fungus and its biochemical origin appears to follow condensation of oxalacetate and acetate. Lastly production of citrmin as another metabolite has also been reported.

Both quantitative and qualitative immunochemical methods were used for studying the mutual relationships of several spocies and the subspecies of the genusPhaseolus: Ph. vulgaris L. ssp.vulgaris, Ph. vulgaris L. ssp.aborigineus Burk.,Ph. coccineus L.,Ph. acutifolius A. Gray,Ph. lunatus L. (American endemites) andPh. aureus L. (a typical Asian bean). Protein characters of cotyledons (i.e., "storage" proteins) of the above species were compared with the aid of antisera prepared against seed (cotyledon) proteins ofPh. vulgaris L. ssp.vulgaris, cv. Veltruská Saxa, using
(a) the whole complex of cotyledon protein,
(b) the albumin fraction of this complex,
(c) the globulin fraction,
(d) crystaline phaseolin.
Our results are in agreement with the morphological and genetic data ofBurkart andBrücher on the close relationship betweenPh. vulgaris L. ssp.vulgaris andPh. vulgaris L. ssp.aborigineus (both contain a character designated asPh. vulgaris protein 1 which is lacking in the others, both contain an identical phaseolin and exhibit only negligible differences in the specificity of proteins). The closest to these two species isPh. coccineus (almost identical phaseolin, small differences in the albumin and globulin fractions, a greater quantitative difference in protein specificity).Ph. acutifolius contains a somewhat different phaseolin, exhibits greater deviations in the albumin and globulin fractions and a greater quantitative difference in protein specificity.Ph. lunatus andPh. aureus are quite different in all the above respects. These data are in good agreement with genetic data (crossability).

In both types of crosses (3n C.G.×4n D 154 and 4n D 154×3n C.G.) pods were found to set. In the first case pods shed within 4 days. In the second case pods were found to persist till maturity. Only a few uppermost ovules were found to be fertilized. Pollen tubes were seen to reach the ovules within 24 hours.
In 4n D 154×3n C.G. fusion of sperm with the egg was not noted to be complete till 3 days but the secondary nucleus is fertilized by other sperm. In 3n C.G.×D 154 fusion of sperm with egg or with polars was not complete within 3 days. Signs of degeneration of ovules were noted on the 5th day in both cases.

Mosaic disease ofAnchusa officinalis found at a ruderal association in Prague-Holešovice in the close proximity of TMV infected cruciferous weedsCardaria draba andSisymbrium loeselii, was identified to be caused by the same agent-the necrotic TMV-strain.

The effects of various cultural factors on the secretion of three pectic enzymes (PP, PG and PE) byAlternaria tenuis on synthetic media were studied. The results can be summarised as follow:
1. No definite correlation between the secretion of pectic enzymes, pH of the medium and the growth of the fungus was observed.
2. The secretion of the enzyme was dependent on the presence of pectin in the medium.
3. While various sugars were found to be equally effective, production of the enzymes was better on a medium without any sugar.
4. After varying the various concentrations and constituents of the medium, the following medium was found to be the best for the enzyme secretion: 1% pectin, 0.2% asparagine, 0.05% magnesium sulphate and 0.3% potassium dihydrogen phosphate.
5. It was established that on the above medium the fungus required four days of incubation at 25°C for the secretion of most active pectic enzymes.

Substances inhibiting local infection with virus X were isolated from leaves of potato cultivars Saphir, Saco, and Blaník by means of ultracentifugation and were concentrated with ammonium sulphate. These inhibitors were effective if rubbed into leaves of some host plants at least 2-4 days prior to infection without using any abrasives.

The calculation and construction of a simple nomogram to be used instead of a set of two equations in a two-wavelength spectrophotometric determination of chlorophyllsa, b, their total amount and ratio is are described. Any pair of equations can be represented nomographically by this construction.

In unseren Versuchen haben wir die Wirkung der 3 isomeren Styrylpyridine und des bekannten Herbizidstoffes 3-Amino-1,2,4-triazols (AT) in der Konzentration 10^-3 m auf die Succinat-dehydrogenase und Succinoxydase-aktivität der Wurzel vonSinapis alba untersucht. Styrylpyridine hommten das SDH-Enzymsystem vollständig, falls sie zum Pflanzenhomogenat noch vor der Messung der Aktivität hinzugefügt wurden. Diese Stoffe zeigten die gleiche Hemmwirkung wie Malonat. In den Versuchen, wo die Pflanzen direkt in den Versuchslösungen kultiviert wurden, zeigte sich 3-Styrylpyridin als das wirksamste; weniger wirksam war 4-Styrylpyridin und am wenigsten wirkte 2-Styrylpyridin. Die gleiche Abstufung der Wirksamkeit lieferten auch die Wachstumsteste und die Untersuchungen der SO-Aktivität. Die Succinoxydase-aktivität war nur wenig beeinflust, falls die Substanzen dem Pflanzenhomogenat beigefügt wurden. Bei den Pflanzen, die in den Versuchslösungen kultiviert wurden, zeigte sich die gleiche Abstufung der Hemmwirkung der SO-Aktivität wie bei dem SDH-System. AT beeinflusste das SO-Enzymsystem überhaupt nicht und das SDH-Enzymsystem wurde im Gegenteil noch stimuliert.

In experiments with fodder cabbage and sugar beet the influences were tested which restrict the finding of a uniform linear dependence between the chlorophyll content and photosynthetic rate. The main factor is most probably the irradiation during the growth of plants and the measuring of photosynthetic rate. Changes in the density and length of irradiation with the proceeding spring season are reflected in the decrease of unit chlorophyll activity in all leaves of the plant. Such differences were not observed in plants grown in winter months at a low greenhouse irradiation density. High irradiation density during the measurement of photosynthesis ensures the finding of high correlation of photosynthetic rate with the chlorophyll amount per unit area of leaf. With a low irradiation density, or in thick leaves, the lower layers of chloroplasts are not saturated with radiation, and hence a higher correlation coefficient is found by relating photosynthetic rate to the percentage of chlorophyll in dry weight than to the quantity of chlorophyll per unit area of leaf blade. In some experiments higher activity of chlorophylls was found in young leaves before they have reached the state of "photosynthetic maturity" than after this turning point. This difference diminished by relating the photosynthetic rate to chlorophylla content instead of the total amount of chlorophylls (a+b). High activity of chlorophylls in very young leaves and great individual variability within the experimental plant groups caused by uneven cultivation conditions are the basis of apparent sigmoid character of average curves for the chlorophyll-photosynthesis relation.

Comparison with the findings in the cells of other plants and animals showed that the endoplasmic reticulum in the root apex ofFagopyrum has the same general character and function as in other biological objects, i.e. in secretory processes and especially in this case in the transport of the substances produced. Detailed studies of the morphology and activity of the endoplasmic reticulum showed some functional differences which are characteristic for this object. The endoplasmic reticulum participates apparently in the transport of the mass of known but functionally and nomenclatorically controversial formations which here are called dense bodies. Dense bodies exist inFagopyrum in a considerable amount as compared to other objects. Frequent contact of the dense bodies with the ends of the endoplasmic reticulum, contact with the endoplasmic retieulum passing through the plasmodesm, accumulation of the dense bodies along the cell wall and in proximal distance of the plasmodesms and intensive staining of some plasmodesms was observed. The dense vacuoles in this object represent dilated spaces of the endoplasmic reticulum which apparently have the function of reservoirs of the dense mass. The endoplasmic reticulum in the calyptra cells appears to participate in the formation of the cell walls. This object differs hereby from others, where the participation of the Golgi apparatus has been observed in this function.

Stimulation and inhibition of photosynthesis inHydrilla verticillata Presl. with quinine sulphate and quinine alkaloid with concentrations ranging between 0.001 and 100 ppm was observed. Quantitative measurements of photosynthesis were done by a microburette (Audus 1940) and qualitative estimations by the modified apparatus byZutshi (1965a). Maximum inhibition of 50% and 34% is obtained with 100 ppm of quinine sulphate and quinine alkaloid respectively. The inhibition is due to the adverse effect on the pigment system particularly on carotene (Zutshi 1963). Forty percent stimulation of photosynthesis is obtained with 0.01 ppm quinine sulphate and 12.5% with 0.001 ppm quinine alkaloid. Difference in the biological activity of these two alkaloids is due to their different chemical structure and purity.