The metabolism of exogenous tryptophane (3. 10^-2M) and β-indoleacetic acid (3. 10^-2M) in extirpated wheat embryos was studied chromatographically and electrophoretically.
It was established that the external application of β-indoleacetic acid in wheat embryos leads to the formation of its complex, indoleacetylaspartic acid. Chromatographical demonstration of the components of the complex was made foliowing alkaline hydrolysis.
A complex compound also arises from exogenous tryptophane, which again frees tryptophane following alkaline hydrolysis. The assumption has been put forward that this is malonyltryptophane, reported by Andreae and Good (Dannenburg andLiverman 1957). The isolated finding of a further substance may be mentioned, which possesses similar chromatographic properties to those of the indole complex-ascorbigen. For reasons so far unknown, this substance has not been isolated again in wheat plants.

Results of the action of low doses of gamma irradiation, intensity 1-80 to 0-24 r/day, are recorded in this paper. Irradiation was carried out on a gamma field with a 0-50 g. equiv. Ra Co⁶⁰ source throughout the whole vegetative cycle.Trifolium pratense var. Jičínský was chosen as the experimental material. Growth and the yield of green matter was followed both on individually bedded out plants and on sown plots. Results of the measurement and weighing of the plants were statistically evaluated by means of the t-test and analysis of variation. Small, daily radiation doses (1.80-0.30 r per day) produced a significant stimulatory effect which was evidenced in the greater height of the irradiated plants as compared with the controls and a higher yield of green matter. In conclusion the paper deals with work that has already been carried out in this field. Experiments and measurements have shown that low doses of chronic gamma radiation are capable of stimulating plant growth. This work is confirmed by result obtained by Breslavets, Berezina and Shchibrya (1956) on other material.

1. During the period from June 11 to August 6, 1957 IEP_M values were recorded for the meristematic tissues of growing points of apex buds of brachyblasts and for phloem and xylem of brachyblasts and growing spurs of apple varieties Transparent Yellow, Lord Lambourne and Watervliet.
2. For a period of 7-14 days before the morphological differentiation of growing points of flower buds the shift of IEP_M values towards the area of higher pH was observed. This shift was found both in the meristematic tissues of growing points and in the phloem and xylem of brachyblasts and growing spurs.
3. After reaching a certain limit a shift of IEP_M values back to the area of lower pH at the original level was observed.

This paper gives a description of a two-channel photoelectric planimeter for measuring leaf areas. It is based on the absorption of rays within the range 0.6 to 1.4μ. The flux of radiation is converted to electric signals by argentum sulphide photocells. The difference in the photoelectric currents from the measuring and control channels is amplified by a sensitive and highly stable d.-c. differential amplifier and is indicated by a meter which can be calibrated direct in area units.

The paper describes a new strain of tobacco mosaic virus which has been named S-strain of TMV because of its characteristic stripe symptoms. The Al-strain of tobacco mosaic virus was used as the initial material.
In contrast to methods used hitherto the S-strain was obtained by interfering with the metabolism of the host plant by a change in the environment. (SvobodovÁ 1954, 1958). The usual hosts of tobacco mosaic virus were used, chiefly tobacco and tomato plants. These plants were cultivated under aseptic conditions on an agar medium in Erlenmeyer flasks with a reduced amount of nutrients, a shortened period of illumination and a limited air supply, so that they were stunted. Following the passage of the initial Al-strain of TMV through these dwarfed plants changes in symptoms appeared, which became apparent only after further passages through plants grown under normal conditions in a glass house in garden soil, where the virus once again had normal conditions for reproduction. Of the new symptoms obtained, only the most striking were further studied (the symptoms of S-strain). By means of alternating of the passage of the Al-strain of TMV from normal-to dwarfed-to normal plants grown under artificial nutrient conditions, i. e. a twice or thrice repeated sudden change of environment, the new strain (S-strain) was obtained five times in all and at different times of the year. From the symptomatic point of view no differences were found in the different repetitions of this change. The results were also the same for material from tomato plants and from tobacco of the Samsun variety.
The origin of the new strain was not caused only by the stuntedness of the host plants. It was also necessary to influence its metabolism by an abnormal environment (particularly insufficient air) in the Erlenmeyer flask before and after inoculation.
Following the reverse passage of the S-strain from plants grown normally in a glass house to dwarfed plants in an artificial environment no further changes occurred. Neither did the passage to ten other hosts grown normally on garden soil and in artificial nutrient produce any further change in symptoms. The S-strain has been maintained by a succession of continuous passages throughNicotiana tabacum Samsun for six years, and each year mass inoculation of a large number of plants is carried out. We therefore now consider the change to be permanent.
Indirect influencing of the virus through a change in the metabolism of the host plant sufficed for the induction of the new strain. Its symptoms appeared only after passage through normal unaffected plants, where the virus reproduction was not inhibited by the retarded growth of the host plant. There is a certain similarity in the emergence of the S-strain and the TM44-stram, obtained byPfanchuch et al., with X-ray irradiation. However, the initial material was the ordinary green strain of TMV.
The biological, chemical and other characteristics ascertained for S-strain and a comparison of these with the characteristics of the initial Al-strain and the ordinary green strain of TMV will be published later.

1. Anagallis arvensis L. (im weiterenA. a.) besitzt eine niedrige Keimfähigkeit, aber lässt sich leicht vegetativ vermehren und pfropfen. Beim Pfropfen "auf die Flasche" ist die Inkubationsdauer kurz, minimal bis 8 Tage. Die Pfropfung "übers Kreuz", das heisst das Durchziehen des abgeschnittenen kranken Stengels durch eine Längsöffnung im Stengel, der gepfropft wird, ist nur theoretisch von Bedeutung.
2. Die Blüten gesunderA. a.-Exemplare schliessen sich bei Nacht. Die fransenförmigen Blüten bleiben länger geöffnet. Blüten mit reduzierten Blütenkronen besitzen nicht abfallende, Monate lang geöffnete Kronen. Bei uns beginntA. a. in der freien Natur gegen Ende Mai zu blühen, im Glashause, sobald die Tageslänge 12^1/2 bis 13 Stunden ausmacht.
3. Der Virusspiegel ändert sich in denA. a.-Pflanzen je nach der ontogenetischen Entwicklung der Wirtspflanze im Zusammenhang mit ihrer Periodizität. Zur Reproduktion des Virus kommt es erst, wenn die Tageslänge mindestens 12 Stunden erreicht hat. Die Viren dieser Gruppe können in den Pflanzen auch latent vorhanden sein.
4. Bei Liptovský Hrádok in der Slowakei haben wir eine FormA. a. mit kleinen rostrot gefärbten Kronen gefunden. Die ersten Anzeichen einer Erkrankung vonA. a. an Vergilbung traten bei uns Ende Juni 1957 und im Jahre 1958 erst Ende Juli in Erscheinung. Die krankenA. a.-Exemplare bilden keimfähige Samen nur in den unteren Kapseln, die sich vor der Infektion entwickelt hatten. Die Virose kann in der Natur einen entscheidenden Einfluss auf die Frequenz vonA. a. haben.
A. a., Stellaria media undVeronica chamaedrys können Indikatoren der Anwesenheit von Viren und Virosen aus der Gruppe der Akarpien sein (Stolbur, Vergilbungen, purple-top und yellow-top bei Kartoffeln).Stellaria media kann als überwinternde Pflanze, die selbst Fröste (mindestens-25°C) verträgt, eine Reservoirpflanze der Viren dieser Gruppe sein.
5. Zu Prolifikationen beiA. a., kommt es von September bis November. Zuerst werden dabei auch die Blüten, später nur die Blätter gebildet.
6. Die Fransenförmigkeit der Blütenkronen beiA. a., kann eines der ersten Anzeichen von Vergilbungserkrankung sein. Es tritt bei übertragung der Hexenbesenkrankheit der Kartoffeln, der green petals der Erdbeerstauden, der Phyllodie bei Kleearten und bei Plantago major in Erscheinung, sowie auch bei Pflanzen, die an bakteriellem Braunwerden der Stengelbasis leiden, sodann auch vorübergehend als mögliche Intoxikationsfolge der fremden Unterlage nach einer Pfropfung gesunderA. a.-Exemplare auf fadenförmige Kartoffelkeime.
7. A. a.-Exemplare, die sehr schwer an Virose erkrankt sind, blühen überhaupt nicht, verzweigen sich aber stark und bilden anstelle der Blüten Blattrosetten.
Verengung, Welligwerden und Anthokyanisierung der Blätter sind nicht immer charakteristische Kennzeichen für eine Vergilbungsvirose vonA. a.
Pfropfreiser krankerA. a.-Exemplare riefen beinicotiana glutinosa wahrscheinlich infolge einer heftigen Intoxikation und eines raschen Absterbens der aufgepfropften Pflanzenteile vonA. a. keine Krankheitssymptome hervor.
Pfropfreiser krankerA. a.-Exemplare bewirkten bei jungen Sämlingen v

Die Autoren bringen eine kurze Mitteilung uber Beobachtungen der sofortigen Veränderungen in den Zellen der Epidermis von Allium cepa durch Ultraschallwirkung. Als Beobachtungsmethodik dieser Veränderungen wurde die Fluoreszenzmikroskopie mit Akridinorange-Pärbung verwendet. Es werden vier Stadien der hervorgerufenen Veränderungen unterschieden. Auf Grund dieser Beobachtungen wird angenommen, dass die quantitative Ausbeute der Energie des Ultraschalles für biologische Vorgänge verschieden sein kann, auch wenn in den sekundären Vorgängen die Ultraschallwirkung entweder zum Absterben oder Überleben der Zelle führt. Aus zytologischen Beobachtungen wird auf kolloidal-osmotische Veränderungen geschlossen.

This paper presents a summary of new evidence for regarding sterility and dwarfing of oats (OSDV) as a virus disease. Brief references are also made to the identification of a further virus in Czechoslovakia-the wheat striate virus (WSV). Both viruses are transmitted by the leafhopperCalligypona pellucida F. The wheat striate virus differs from the oat sterile-dwarf virus in that it can be passed transovarially by the infected females of the vector to their progeny. This characteristic, which made it possible for the two viruses to be separated from each other, was demonstrated for the first time for pathogenic viruses on the European continent in this case. OSDV can be transmitted by leafhopper larvae and adults. The time during which OSDV circulates in the vector's body is very variable; it is usually three to four weeks. The incubation period of OSDV was three to four weeks for oats, four to seven weeks for wheat and barley; rye only showed retarded growth after four weeks. For infection to take place it was necessary for the vector to remain for a minimum of half-an-hour on the test plant; 100% infection was obtained when the vector remained on the plant for three days. The injury inflicted by OSDV on the host does not increase proportionately either with the duration of the feeding period or with an increase in the number of vectors on the plant. Concentrated extracts of the crushed bodies of infectious leafhoppers produced no symptoms of disease, when rubbed or injected into oat plants. Nor were attempts to transfer OSDV and WSV through soil or dodder successful. OSDV was, however, transferred by grafting. Both viruses gave rise to characteristic symptoms inAvena fatua L. andPoa annua L. These findings are discussed from the etiological point of view.

1. The influence of varying concentrations of gibberellic acid on seedlings of wheat, lettuce and oats (up 10 days old) was observed and optimal concentration of 10 to 100 μg GA/ml. was established. Biometric evaluation of the experiments showed significant stimulation of the overground parts with all concentrations used (0.1 to 100 μg. GA/ml.) and significant inhibition of bhe roots with concentrations 1 to 100 μg. GA/ml.
2. For lettuce only the concentration 10 μg. GA/ml. was used. In this case, too, increase in length of overground parts was significant and inhibition of root growth was observed. For oats the stimulating effect of GA was recorded for both overground parts and roots.
3. Fresh weight of wheat was stimulated only by concentrations of 100 μg. GA/ml. In the case of lettuce (where values of fresh and dry weight were taken for the whole plant) we found a marked stimulation of fresh weight and a somewhat smaller increase in dry weight.
4. Observation of the dynamics of growth in length of overground parts and roots and increase or fresh and dry weight in lettuce showed a mutual relation between the values recorded in control and experimental plants in the period of 4 to 10 days following germination.

Hemp (Cannabis sativa L.) was sown at intervals from November to August. For each sowing the time of flowering was recorded for male and female plants separately. Male plants usually flowered earlier than female. When the period of daylight exceeds 14 hours, that is when the days are lengthening in April, the female plants stop flowering and continue their vegetative growth. They start flowering again when the days are shortening considerably, in August, when the daylight period is about 15 hours. The male plants flower even when the day is longer than 14 hours.
In experiments during which the plants were shaded it was found that reduction of light intensity leads to an increase in the number of female plants, particularly if shading is carried out in the early stages of the plant's development.
The occurrence of intersexual plants was observed only during the short day period (11 to 13 hours), when they composed 22-30% of the total. When the day exceeds 13 hours intersexual plants no longer develop.
The grafting of plants of varying sex did not produce any sexual change-probably due to the fact that the period of vegetative approximation was short.

1. The symptoms caused by the S-strain(Svobodová 1954, 1958, 1959) were described for ten hosts and compared with those caused by the Al-strain and the ordinary green strain of the tobacco mosaic virus. In all the host plants tested the S-strain produces symptoms different from those caused by other strains.
2. A comparison of the incubation period and the effect on growth ofNicotiana tabacum Samsun, the behaviour onN. rustica and quantitative tests onN. glutinosa showed that the S-strain is the least pathogenic of all the strains compared.
3. Results of biological tests show the S-strain to be most similar to the ordinary green strain of tobacco mosaic virus, only serological and cross-protection tests indicate a closer relationship to the Al-strain, from which it developed.
4. The behaviour of the S-strain of TMV in expressed sap is similar to the behaviour of the ordinary green strain and of the Al-strain. The range of hosts for all three strains is also the same.Physalis alkekengi andP. Franchetti are to a certain extent differential hosts.
Thus biological tests show that the S-strain is a new strain of tobacco mosaic virus.

1. Leaves of sugar-beet (Beta saccharifera), which had assimilated active carbon dioxide C¹⁴O₂, were subjected to the process of humification in soil. After three to five months of humification the dried soil was extracted with ether-alcohol, then with sodium or potassium hydroxide; the humic acids were separated from fulvic acids with hydrochloric acid. All fractions were radioactive.
2. Maize plants (Zea mays) grown in diluted Knop's solution with the addition of active humic acid showed radioactivity in the roots and leaves. There was, however, a marked difference between the roots and the leaves. While the activity of the roots after two to twelve days was about 100 to 200 cpm., that of the leaves was about 20 cpm. as calculated for one plant, or about 300 cpm./10 g. for roots and at the limits of measurement for leaves.
3. When a drop of solution and suspension of active humic acid was placed on the lower surface of the first leaf, it spread very little even in this leaf; the activity of the second and third leaves was at the limits of measurement after five days; the same applies to the roots.
4. Autoradiograms were fully in keeping with the results obtained with the counter. Roots were clearly marked and more or less intensely, while the leaves did not appear or appeared only as faint shadows.
5. These experiments do not resolve the question of whether unchanged humic acid penetrates into the cells. It can only be concluded, on the basis of these experiments, that if radioactive humic acid is added to water or to nutrient solution, radioactivity appears in the roots and later weakly in the leaves. If it is assumed that the activity measured in the plant organs was caused by humic acid applied direct, this means that it penetrates into the plant slowly, it is not accumulated and spreads throughout the plant slowly from the roots.

Für die vorliegende Arbeit wurden die Weizensorte Podbořanka und Těšover Korn benutzt. Der Versuch verlief unter Feldbedingungen bei verschiedenen Pflanzenbestandsdichten. Die schwächste Diehte entsprach der üblichen Norm der Getreideaussaat (400 Getreidekörner auf einen Quadratmeter), die stärkste war fünfmal so dicht. Im Laufe der Vegetationsperiode wurden fünf Messungen durchgeführt. Es zeigte sich, dass die Dichte des Pflanzenbestandes vor allem das Pflanzenwachstum hemmte. Dabei wurden die vegetativen Organe der Versuchspflanzen stärker als die Reproduktionsorgane geschwächt. Eine Erhöhung der Diehte bewirkte zugleich auch eine Herabsetzung des Gehaltes an Chlorophyll, Phosphor und Wasser in den Versuchspflanzen und zwar besonders auffällig gegen Ende der Vegetationsperiode. Die Pflanzen der dichtesten Bestände schöipften weniger Phosphor aus dem Boden, als Pflanzen normaler Bestände. Man kann voraussetzen, dass dies durch eine stark herabgesetzte Sorptionsfähigkeit des Wurzelsystems bewirkt worden ist.

Bei drei Sorten von verschiedener wirtschaftlicher Qualitat, Klarapfel, Wealthy und Ontario, wurde während der Fruchteinlagerung die Vitalität exstirpierter Keime untersucht, und zwar naeh dem Grad der Grünung der Kotyledonen, nach der Wachstumsgeschwindigkeit der isolierten Keimlinge und nach der Wachstumsintensität der Keimwurzeln. Die Beziehungen dieser beobaohteten Charakteristika wurden mittels Faktorenanalyse ausgewertet und mit der als Bioteknose bezeichneten Erscheinung in Verbindung gobraoht.

In homogenates of parts of the plantsCirsium arvense SCOP.,Cineraria hybrida hort.,Reseda odorata L.,Taraxacum officinale WEB. andGladiolus imbricatus L., infected by aster yellows, and inCuscuta europea L., which transferred the aster yellows virus from.Cirsium arvense toPetunia hybrida, similar spherical (polygonal) particles of 30-50 millimicrons, most frequently 35-40 millimicrons, were found. Comparison with homogenates from healthy plants showed that these may be considered to be virospores of the aster yellows virus.

The different components of humus-alcoholic extract, humic acids and fulvic acids-progressively isolated from compost garden soil and deprived of minerál ions by electrodialysis, were, after addition to Sachs's nutrient solution, found to have differing effects on the growth of stems and roots of tomato plants. Similarly, differences in the effect on oxygen intake of leaves and roots was confirmed and varying amounts of chlorophyll were determined in the leaves. Fulvic acids were shown to be more active components of humus than humic acids. Morphological changes in the root system were found to be more typical for an estimation of the action of the different components of humus than the changes in physiological characteristics mentioned above.

Aphids (Myzodes persicae Sulz.) were subjected to infection feeding after starvation for two hours, in varying air humidities. Infection feeding lasted for five minutes. The aphids which were starved under conditions of 0%, 34% and 56% air humidities transmitted the virus to a greater extent than those kept at humidities of 80% and 100%. (At the relative humidity of 0% there was a slight decrease of infectivity, probably due to reduced activity of the aphids). The phenomenon may be explained by the fact than when denied food in a dry atmosphere the aphids lose more water than in a humid atmosphere and hence their rate of feeding when on the source of infection is more rapid, which tends to increase the number of infected individuals. This finding is regarded as having a practical significance.

The mechanism of the cytomorphological effects of low temperatures was studied by the fixation of young leaves ofTriticum vulgare with temperated alcoholic fixatives. Some specimens were plunged into liquid nitrogen, allowed to thaw and fixed; other objects were plunged into liquid nitrogen and fixed without thawing; control objects were fixed directly. At various temperatures of fixatives (-76, -27,+27,+58° C) different results were observed on the objects pretreated in the same manner. It was thus demonstrated that the destruction processes occur, in this case, during thawing.

The aim of this work was to establish under what conditions the water deficit values obtained byStocker's (1929) method can be considered to be those for actual water deficits. It was found that the water intake of detached leaves is not necessarily due only to incomplete saturation of the leaf tissues with water, but that in young leaves it is caused to a great extent by their extension growth. Thus, water deficit in the sense ofStocker's definition is not merely a simple physiological state of incomplete saturation of the tissues, but is expressed by the sum of the need for water to achieve the greatest possible saturation of the tissues and the need for water in the normal course of the extension growth of cells.

Within one leaf blade there are considerable differences in hydration of its parts. Marked longitudinal, transverse and area gradients of the osmotic pressure of cell sap were ascertained within the leaf blade of sugar beet. The osmotic pressure was determined indirectly by the refractive index according to the empirically established correlation refractive index: osmotic pressure (measured cryoscopically) cf. fig. 1. The gradient from the base of the blade to the tip ranged around plus 40% of the osmotic pressure at the base. This and other gradients mentioned were not noticably changed even when the leaves were artificially saturated with water or when water deficit arose or was adjusted by actual changes in the water balance. (In all these experiments the polarity of the transpiration stream was maintained.) The stability found in various degrees of hydration of individual parts of the adult leaf blade indicates that the variability is a result of the previous ontogenetical development of the leaf as a polar organ and of the fact that the adult leaf remains essentially unchanged by the actual changes in the water exchange. The heterogeneity found in the leaf with regard to the values here dealt with is an expression of the physiological heterogeneity of the leaf blade. ation intensity is concerned, it has been theoretically established that only after the reduction of turgor to nought does increased osmotic pressure of cell sap start to act as a factor in reducing transpiration, and that this reduction is under normal conditions comparatively small (Renner 1915, Stalfelt 1956).

1. Attention is called to the possibility of using resoroin blue for the staining of pollen tubes within the style tissue and the method of staining is described.
2. In pollen tubes, the growth of which is inhibited due to incompatibility, there is at least twice the amount of callose relatively to their length as there is in normally growing compatible tubes. In apple this is primarily due to the greater length of the callose plugs, in tobacco also to their greater density.
3. The regularity of the formation of callose in pollen tubes increases with the rate of their growth.
4. It is suggested that the physiological basis of callose formation consists in the limited capacity of pollen tubes to use the pyran components of metabolized saccharose in the process of respiration.