Cyanus segetum LAM. was transferred from a long to a short photoperiodic regime at various stages of ontogenesis and the development of the plant investigated. The morphology of the leaves ofCyanus segetum was dependent on the photoperiodic regime. On a short photoperiodic regime, pinnately sected leaves were formed, but only if development was inhibited while the shoot apex still had a structure characteristic for the vegetative plant. The ability to influence the shape of the leaves by a short day ends before the morphological differentiation of the inflorescence at the time of the disappearance of the vegetative structure and the formation of the meristematic mantle. After this time all leaves were smooth-edged like those of the controls on a long day. Although the ability to influence leaves was limited to the period of initiation of the leaf primordia, it was not restricted to the primordia then being initiated. The conditions of development also affected leaves whose primordia had already been initiated. This was evidently due to the action of photoperiodic conditions via ontogenesis. The position of the axils was also changed in dependence on the photoperiodic regime.

Statmographs were used for determining the curves of weight decrement of severed root tips of the squash (Cucurbita maxima L.) with time and were examined under controlled conditions. The existence of two qualitatively different fractions of water could not be demonstrated by the method used, all the curves obtained displaying a completely continuous character, without any inflexion point. The basic shape of the curves remained preserved on desiccation at different temperatures (20-40° C), at different relative humidity (45-90%), with plants of different age and different composition of aqueous media (Knop's nutrient solution, calcium-free medium, distilled water). Not even a 0.01% solution of potassium humate which significantly raised the water content of root tissue affected the shape of the desiccation curves. A continuous release of water was also observed when the meristematic root zone and the zone of longitudinal growth were dried separately.

Quantitative determination of chlorophyll a and β can be made by paper chromatography of acetone extracts of plant material with colorimetric measurement of the eluates from the separated zones.
From the suitable solvent systems which give adequate separation of the pigments at a distance of 20 cm. from the start,Hager's mixture (1955) separates the chlorophylls better than the toluene-isopropanol (400: 1 v/v.) mixture, which, however, is better for the separation of carotenoids. Twice the amount of chlorophyll is separated on Whatman 31 ET paper, equally well and with the same time of development, as on Whatman No. 3 paper, on which it is possible to separate a maximum of about 15 μg of chlorophyll pigments per 1 em. start length. Losses on elution are, however, higher on using Whatman 31 ET paper. In plants with a high chlorophyllase activity, the error of determining chlorophyll a andb is greatly reduced if the leaves are placed for 1 min. in boiling water before extraction. For elution of chlorophylla andb from paper it is better to use anhydrous acetone, for chlorophyllides 80% acetone.
A comparison of the procedure investigated with the method of two-wave length spectrophotometric measurement of crude acetone extracts showed that in view of the average 10% loss, the chromatographic method is hardly suitable for determining the absolute amounts of chlorophylla andb, although the relation (a/b) can be determined with similar precision by both methods. Moreover, in view of the greater amount of work involved the chromatographic method can only be recommended for confirming the results of spectrophotometrie determination. Quantitative determination of chlorophylls from the area of the spot or from the "R_F" value can only be of an informative character.

The growth OfRhizoctonia solani in different carbohydrates was studied. The rate of growth of the fungus was traced by taking the dry weights of mycelia obtained from the carbohydrate medium at regular intervals and shifts in the pH were recorded. Different carbohydrate sources had different effects on the growth of the organism. The exoenzymes from the organism were capable of cleaving carbohydrates irrespective of whether the fungus grew in them or not.

An investigation was made of the anatomical structure of the shoot apex of wheat in the first four stages of organogenesis according toKuperman (1961). It was found that the shoot apex is first covered only with dermatogen (first stage). Then the hypodermis gradually differentiates (second stage) followed by differentiation of the subhypodermis (third stage). In the first stage, the central core of the apex is formed by more or less uniform isodiametric cells so that no zones are distinguishable. During the initiation of the primordia of the assimilating leaves, i.e. in the second stage, a group of larger cells was observed in the apical part of the hypodermis and can be compared with the central zone described in dicotyledons. Under it there is a characteristic group of smaller cells. In the third stage the differences between these groups of cells become less clear and in the fourth stage are no longer observable. No differences were found in the manner of initiating the leaf and bud primordia during the period of ontogenesis studied. There is, however, an alteration in the extent of growth between the bud primordium and the corresponding leaves. Short-day photoperiodic inhibition, always started on the days when the shoot apices were collected for anatomical study, showed that the determination of the primordia of the leaves and axillary buds as parts of the inflorescence is complete by the end of the third stage, at the time when the primordia in the central part of the ear are initiated

Six-day leaves of wheat (Triticum vulgare) were used to test the effect of oxygen, nitrogen and different mixtures of these gases, methylene blue and L-cysteine on the inhibition of respiration by sodium fluoride and monoiodoacetic acid using the Warburg manometric method. In an atmosphere of 100% oxygen total respiration was increased by an average of 45%, 10% oxygen led to a decrease in respiration by 20%. However, no simultaneous changes were found in the degree of inhibition by these enzyme poisons. On decreasing the oxygen content to 5% inhibition of respiration was almost doubled while at the same time respiration fell by an average of 23%. In nitrogen, the respiration rate varied around 10% and inhibition was almost 100%. The results showed that the action of enzyme poisons is only influenced by different oxygen content at low oxygen tension and is evidently associated with the dominance of a given energy system (glycolysis).
On using methylene blue and L-cystein in concentrations of 10-3M a decrease in the relative inhibition of respiration by enzyme poisons was also found. The total respiration rate, however, was only raised by 6-8%. Since the change in the degree of inhibition on using these substances is caused by an increase in the participation of respiratory processes resistant to glycolytic inhibitors it can, in this case be assumed that there is an increase in the activity of the pentose cycle in such tissue.

The pathophysiology of tomato plants infected with potato witches' broom was studied. Changes in dry weight, content and composition of ash and the amount of different phosphorus and nitrogen fractions were investigated. All analyses were carried out separately in leaves, stems and preliminarily also in flowers. Considerable disproportions found in the distribution of metabolites among the individual organs investigated correspond to a great extent to the morphological picture of the disease. The leaves of diseased plants are actually starving and their growth and development are greatly inhibited. On the other hand, the stems are overflowing with metabolites, in particular with nitrogenous ones. They are thickened and along their entire length rootlets and sprouts appear forming the characteristic brooms. The authors assume that the disturbances in flower formation in diseased plants are due to the lack of essential metabolites. Diseased plants contain an increased amount of alkaline metals and alkaline earths.

1. The relation between the manifestation of the factors for the row number, development and fertility of lateral florets and kernel weight of barley was investigated.
2. Kernel weight was found to depend on the number of rows as well as on the development and fertility of the lateral florets.
3. The possibility of a genetic linkage between the factors for row number and kernel weight was discussed.

As lipids can be a source of artefacts during intracellular localization of enzymes by cytochemical methodsin situ it was the aim of the present work to obtain orientation data on the distribution of lipids in the meristematic plant cells. The different fixation and object embedding methods examined revealed that it is best to fix the material by some formol fixative and without chroming, to embed it in polyethyleneglycol media. An alcoholic solution of Sudan black was found to be most reliable. In the meristematio cells the cytoplasm is usually stained more intensely than the nucleus. The ground cytoplasm is stained weakly while cytoplasmic particles are stained intensely. In some cases an intense black staining of nuclei, particularly in the prolongation zone, can be achieved. The staining intensity of cell components does not decrease on extracting lipids with pyridine. After extracting the dye from stained cell components a browninsh residual coloration remains. Chromatography of Sudan black revealed in all the samples tested slowly moving spots (blue and violet) and rapidly moving ones (red II, yellow, red I, colourless).

Im Jahre 1900 veröSentlichte ich einen vorläufigen Bericht über durch Schwerkraft bewegliche Stärkekörner in bestimmten Pflanzenzellen, die man als tierischen Statozysten analoge Vorrichtungen ansprechen könnte. Über diesen Gegenstand erschien 1901 meine ausführliche Arbeit, in welcher ich eine auffallende zytologische Reaktion beschrieben habe, die in stärkeführenden Columellazellen der Wurzelhaube bei geotropiseher Reizung erscheint: Diese Reaktion, welche ich als ein Symptom, dass die erwähnten Zellen den Schwerkraftreiz zu rezipieren vermÖgen, betrachtete, wurde später sehr selten nachuntersucht und ist vergessen worden. Erst im Jahre 1962 veröffentlichte AUDUS neue Angaben über dieselbe und zwar auf Grund von elektromikroskopischer Untersuchung der Statozyten in Wurzelhauben.
Die vorliegende Mitteilung bringt zum ersten Mal mikrophotographische Aufnahmen der zytologischen Georeaktion und erwähnt neue Versuche, welehe zu Gunsten der Ansicht sprechen, dass die zytologische Georeaktion durch Druck der Statolithen auf die äussere Zytoplasmahaut der Statozyten ausgelöst wird. Es wird auch darauf hingewiesen, dass nicht nur spezifisch schwerere, sondern auch spezifisch leichtere Körperchen als Statolithen, welche eine Georeaktion auszulösen fähig sind, fungieren könnten.

A water-soluble germination- and growth-inhibitor present in plants of Brassica genus was studied. Aqueous eluates from chromatograms of methanolic extracts of Savoy cabbage, cabbage and Brussels' sprouts leaves, and of Brussels' sprouts roots, inhibited the growth of wheat; the chromatographic behaviour of this inhibitor was similar to that of the thioglycoside glucobrassicin (GLUBR). GLUBRat 10^-3 m, and the supposed product of its enzymatic degradation, 3-indolylacetonitrile (IAN) at 10^-4 m, inhibited the growth of wheat and clover in a similar manner. At lower concentrations, both substances gradually enhanced growth. In contrast to IAN, GLUBR did not appreciably influence the growth of Savoy cabbage. Other products of GLUBR degradation, such as thiocyanate ion and ascorbigen, influenced the growth to a lesser extent and in a different way. At higher concentrations GLUBR and IAN also inhibited the germination of clover seeds. The biological effect of GLUBR is dependent on the presence of the indole nucleus in its molecule; the thioglycoside glucoiberin, which is not of indolic character, does not influence growth. The presence of free myrosinase was shown in intact wheat seedlings. Hence, GLUBR taken in by the germinating plants must undergo enzymatic cleavage. The in vitro activity of myrosinase in wheat and clover was lower than in Savoy cabbage, but the quantity of IAN formed at a pH corresponding to the natural pH was higher in wheat and clover than in Savoy cabbage, where the formation of the growth-inactive ascorbigen prevailed. On the basis of these results the hypothesis was formulated that GLUBR, the indolic complex from the generaBrassica, Raphanus, Cochleria, Nasturtium, Barbarea andSisymbrium, is a representative of a class of potential inhibitors of growth and germination, whose activity can be explained by the liberation of large amounts of growth-affecting substances during their specific enzymatic cleavage.

An investigation was made of the anatomical structure of the shoot apex ofSenecio vulgaris L. a photoperiodically neutral plant, and compared with the formation of successive leaf primordia along the axis up to the initiation of the terminal inflorescence. In the shoot apex of a germinating plant a central zone can first be distinguished from the peripheral zone which is composed of small and intensely stained cells. Later, a rib meristem appears. At the time of the initiation of the middle (the largest) leaves, the shoot apex has a distinct small central zone and a well developed peripheral zone and rib meristem. Between these zones there is a group of cells dividing in all directions, the subcentral zone. At the time of initiation of the last leaves, the central zone extends to the flanks and gradually ceases to be distinguishable. At the same time, the subcentral zone increases in size. This is caused first by cell division and later, with the initiation of the last, most reduced leaves, by enlargement of the cells. Vacuolization in the inner part of the apex and the arrangement of the superficial cells in rows parallel to the surface of the apex, is a preparatory step to the initiation of the inflorescence.

A very low, for the most part unmeasurable glutamic-aspartio transminase activity and a very high glutamic-alanine transaminase activity was found in the overground parts and roots of young wheat plants. The roots had a higher glutamic-alanine transaminase activity than the overground parts in the first and second leaf stage.
Plants cultivated in Knop's nutrient solution (variant with humate and without) showed a higher glutamic-alanine transaminase activity than poorly growing plants, cultivated in distilled water (with humate and without). In plants cultivated in nutrient solutions, transaminase activity increased with the age of the wheat plants.
As in the previous experiments, the effect of humate was only significant, in the roots of plants cultivated in distilled water with humate, where transamination activity was greater than in the control without humate. The roots of this variant with a stimulatory growth effect showed a large accumulation of free sugars in the previous experiments.
The connection between these effects of humate on the roots of young winter wheat plants is discussed.

A study was made of the effect of substituting a short day for vernalization as a varietal characteristic of winter wheat. Varieties representing certain ecotypes were vernalized for different lengths of time and it was studied how a short day can replace or accelerate vernalization. At the same time data were obtained on the effect of a short day on individual criteria of growth. The results showed that there are ecotypes in which a short day does not replace vernalization (the varieties San Pastora and other Italian varietis). In this case growth inhibition did not occur either. Otherwise it usually accompanies the substituting affect of a short day. This finding permits the interpretation of varietal differences observed in association with short day growth inhibition and changes in carbohydrate metabolism conditioned by it. Growth inhibition produced by a short day is a general reaction which is not only associated with vernalization. The author found varieties (Chlumecká 12) in which growth was inhibited by short day without accelerated development occuring (alternative types).

The seeds contain such a high percentage of phosphoric acid that it interferes with the obtaining of correct results in analysis. Its prior removal from the solution of ash is therefore necessary. A new method is suggested for the entire analysis which is a combination of percolation through an ionexchanger column and colorimetric and gravimetric determination.
The oxide values and the average content of ash per 100 g. dry weight of seeds ascertained by analysis were used to calculate the weight of each determined element per 100 g. of dried substance.
The analysis showed that traces of tin are present in the ash of the seeds tested.
Under the given conditions each species maintains its characteristic way of storing ash constituents in the seeds and this is not obviously affected by the affinity of the plants or the influence of the soil.

The barley variety "Browarny P.Z.H.R." was grown in pots. Experiments on the course of development were conducted for two years. The increase in the dry weight of roots, leaves, stems and grain was recorded. The assimilation area of the plants was measured periodically and the rate of respiration in detached leaves was determined. Photographic records were kept of growing point and ear development. The dynamics of growth and development were studied during the whole vegetation period. The present results are similar to those previously obtained for spring wheat. The short period of leaf activity is the chief factor limiting barley growth.

In der Arbeit wird eine Möglichkeit der Kombination von Humusstoffen mit mineralischen Nährstoffen und Substanzen mit fungiziden Eigenschaften beim Bespritzen von Pflanzen geprüft. Es wurde die fungizide Wirkung der Präparate Heryl, Novozir N, Sulka und Kuprikol, die mit Humusstoffen kombiniert worden sind, an Sclerotinia fructicola (WINT.) REHM., Alternaria brassicae (BERK.) SACC. und Erysiphe graminis var. tritici MARCHAL getestet. Es zeigte sich, dass Humusstoffe die Wirksamkeit der benutzten fungiziden Stoffe nicht herabsetzen. Beim Testen der Wirksamkeit von Novozir N von 0.5 bis 0.03% ist festgestellt worden, dass eine Zugabe von Humusstoffen die fungizide Wirkung des Präparates bis um 12% erhöht.
Weizen, der im Gewächshaus in Wasserkultur gezogen wurde und künstlich mit Erysiphe graminis var. tritici MARCHAL infiziert worden war, wurde während der Kultivierung wöchentlich mit einer kombinierten Lösung gespritzt, die Humusstoffe, Mineral-Nährstoffe, und Novozir N enthielt. Die Ergebnisse zeigen zweifache Wirksamkeit solcher kombinierter Lösungen: eine stimulierende Wirksamkeit der Huminsäuren mit der Mineralstofflösung auf das Wachstum des Weizens und eine fungizide Wirkung auf den parasitischen Pilz. Am allerwirksamsten erwiesen sich eine Doppelkombination von Novozir N mit Humusstoffen und von Novozir N mit Mineral-Nährstoffen. Bei Verwendung aller Kombinationen mit Novozir N konnte die Infektion der Blätter unterdrückt werden, während sie bei anderen Varianten bedeutend fortgeschritten war. Das Wurzelsystem reagierte empf indlich auf das Bespritzen der Weizenblättter.

Zwanzig neu synthetisierte Derivate der Phenoxyessigsäure VII-XXVI, die in der vorgehenden Arbeit (Makovcová, Vaculík 1963) bereits beschrieben worden sind, wurden mittels empfindlicherer Teste bei einer Konzentration von 10^-10 nochmals überprüft. Es wurde der Kressenwurzeltest und derTurfitt-Test mitSacharomyces cerevisiae benützt. Im Vergleich zur Wirkung von neun bekannten Wuchsstoffen Ia-VI unterschiedlicher Wirkungsweise zeigten die geprüften Substanzen weder eine Wirkung auf das Längenwachstum, noch auf die Zellteilung. Bei diesen Untersuchungen zeigte sich, dass die chemische Struktur selbst nicht immer massgebend für die Wirkungsweise ist. Bei den Substanzen, die von uns geprüft wurden, zeigte sich die Art und Zahl der Substituenten im aromatischen Kern für sehr wichtig. Die Resultate dieser Arbeit beweisen, dass der sonst sehr empfindlicheTurfitt-Test eine unge-eignete Methode zur Ermittlung der Wirkung von Wuchsstoffen des Typus 3-Indolylessigsäure (IIa) ist.

Im Rahmen des Versuches wurde der Einfluss des Alters der männlichen und weiblichen (maximal fünf Tage alten) Blüten auf das Geschlechtsverhältnis der Nachkommensehaft beiMelandrium album Garcke untersucht.
Es konnte festgestellt werden, dass der Prozentsatz an weibliche Pflanzen in der Nachkommenschaft zwei Tage alter, bestäubter weiblicher Blüten nachweisbar erhöht schien.
In der Nachkommenschaft bestäubter weiblicher Blüten, die älter als zwei Tage waren, äusserte sich im Auftreten weiblicher Individuen eine absinkende Tendenz.
Das Alter der männlichen Blüten hatte keinerlei Einfluss auf das Geschlechtsverhältnis der Nachkommenschaft.

5-Bromo-2'-deoxyuridine-2-¹⁴C was prepared from 5-bromouracil-2-¹⁴C and 2'-de-oxyguanosine using trans-N-deoxyribosylase fromLactobacillus helveticus and incorporated into DNA ofAllium cepa roots. After isolating the DNA and hydrolyzing it enzymatically to deoxynucleoside-5'-phosphates a radioactive nucleotide was detected which yielded 5-bromo-2'-deoxyuridine-2-¹⁴C on enzymatic dephosphorylation. The incorporation of 5-iodo-2'-deoxy-uridine-2-¹⁴C was followed only by microautoradiography.

Attempts to elucidate the physiological basis of cold-resistance during germination led to the investigation of the germination of seeds at low temperature, the effect of pathogenic and parasitic microorganisms being excluded.
At the various experimental temperatures (4°, 6°, 8°, 10° and 14°C) it was found that seed samples of different varieties of maize respond to conditions close to the temperature minimum for germination in three quantitatively different ways. Firstly, caryopses germinate considerably later than at higher temperatures, secondly, the kernels will not germinate even after a prolonged period, without losing their viability and, thirdly, in some of the caryopses the embryos perish.
The lower the temperature used the greater the inhibition of germination and the higher the mortality of the embryos. The increase in mortality with decreasing temperature indicates that the mortality is primarily due to the actual effect of the low temperature. Samples of seeds displayed quantitative difference in the above mentioned response.
Only when fungicide-treated seed material was used for the cold-resistance experiments was a significant relationship found to exist between this property and the general germinating capacity or mortality at the same low temperature.

In der Arbeit ist der Entgiftungseffekt von Humussäuren und dessen näheres Studium beschrieben. Die Blätter von Wasserpest (Anacharis canadensis [MICHX.] PLANCH.) sterben in der aus gemeiner Quecke (ropyron repens [L.] P. BEAUV.) gewonnenen Agropyrenlösung nach einer Zeit ab, welche von der Konzentration dieses Giftes abhängig ist. Durch Zugabe von einigen Humusfraktionen wird diese Zeit je nach der Konzentration dieser Stoffe mehr oder weniger verlängert. Ein Versuch mit Fulvosäuren zeigte, dass die Schutzwirkung dieser Fraktion auch dann zur Geltung kommt, wenn die Wasserpestblätter vorläufig in ihrer Lösung adaptiert und erst dann der nachträglichen Wirkung der Agropyrenlösung unterworfen werden. Man kann also die Schutzwirkung der Fulvosäuren nicht bloss auf die chemische oder physikalisch-chemische ausserhalb der Zelle durchlaufende Herabsetzung der biologischen Aktivität Agropyrens zurückführen. Sie ist ausserdem auch durch eine von Fulvosäuren hervorgerufene Erhöhung der biologichen Resistenz der Zelle zu erklären.

A laboratory gasometric device for the determination of photosynthetic rate under controlled conditions, using differential measurement with an infrared analyzer which permits the reaching of high precision in the determination of the difference in CO₂ content of the control lair and the impoverished air of the assimilated CO₂, is described. The infrared analyzer, is used so that control air continually passes through one of its tubes and the investigated impoverished air through the other, thus the deviation of the recorder, which can easily be amplified, corresponds directly to the absolute value of impoverishment, i.e. in the case of a known flow-rate, to the photosynthetic rate. Possible fluctuations of the CO₂ content in the control air are recorded by a second infrared analyzer which measures normally, i.e. absolutely.
For the exposure of the plant during the experiment a simple air-conditioned chamber with a controlled temperature (±0.2° C) and air humidity (±2 to 5 per cent of relative humidity), with a controlled high and stable illumination intensity (up to about 3.2×10⁵ erg. cm.^-2. sec.^-1) and the possibility of increasing the CO₂ content of the air, was used.

In jarowisierten und nicht jarowisierten Karyopsen einer Winter- und einer Sommerweizensorte wurden die auxin- und gibberellinähnlichen Stoffe chromatographisch bestimmt. Die Chromatogramme wurden biologisch ausgewertet. Bei der Wintersorte wurden in Bezug auf die Verteilung der Wuchsstoffe keine Unterschiede zwischen der jarowisierten und nicht jarowisierten Variante festgestellt. Bei der Sommersorte bestanden solche Unterschiede. Auf Grund der Versuchsergebnisse wird angenommen, dass die Unterschiede zwischen beiden Varianten der Sommersorte auf eine unspezifische Wirkung der niedrigen Temperatur zurückzuführen sind und dass der Jarowisationsprozess in keinem kausalen Zusammenhang mit einer Veränderung des Wuchsstoffgehaltes steht.

StrainsAspergillus amstelodami No. 5,A. chevalieri A 24 andA. ruber No. 71 were maintained for 21 generations on wort and on Czapek's medium with 20% sucrose by means of monoconidial isolation. A gradual increase in conidium formation was observed which was different on the two media. No decrease in the formation of perithecia or their disappearance could be observed. In strainsA. amstelodami No. 5 on wort andA. ruber No. 71 on Czapek's medium with sucrose, three morphological changes could be detected, characterized first of all by retarded growth and delayed differentiation during the first days of incubation and by reversibility to the original phenotype in some colonies during subsequent generations.A. chevalieri A 21 displayed two different phenotypic changes on wort medium, the changes appearing to be characteristic and permanent. They are accompanied, in addition to other morphological features, by retarded growth and delayed differentiation during the first days of incubation.
The present results are compared with those ofJinks (1954, 1956) and the origin of the changes observed and the effect of media is discussed. As concerns the reversible changes it can be assumed that they are of extranuclear origin since it appears to be justified to rule out changes caused by the mutation of the genome and by segregation of nuclei due to heterokaryosis. With changes where no reversion can be observed the origin is not clear. Increased sporulation is ascribed to changes in the cytoplasm.

Of twenty common oligosaccharides, monosaccharides and sugar alcohols tested, raffinose was found to be the best substrate for growth and respiration of apple pollen tubes. While in a solution of sucrose growth is retarded after about six hours, accompanied by a decrease in respiration intensity, no such decrease was observed in pollen tubes cultivated in a solution of raffinose even after 10 to 20 hrs. of growth. Raffinose is inverted by pollen tubes much more slowly than sucrose which is taken as the cause of the long-term effect of raffinose. Pollen did not germinate at all in a solution of turanose.
It thus appears to be probable that the primary factor in the specific effect of sucrose and raffinose on the growth of apple-tree pollen tubes is the presence of β-D-fructofuranose in the sugar molecule.