A characteristic feature of the effects of humic acids on plant growth is the stimulation of growth in length of the roots. This is sometimes explained as being due to the auxinoid nature of the acids.
The author has examined this assumption by testing segments of wheat coleoptiles and of flax hypocotyls. The growth of segments of both types remained unchanged in solutions of potassium humate in concentrations of 10^-1 to 10^-7 g./l. as compared with the controls in water.
A study was also made of the interaction of humic acids with auxins. The growth curves of segments in concentrations of auxin up to about 20 mg./l. (flax) or 50 mg./l. (wheat) were not altered by the presence of a 10^-1 g./l. concentration of humate in the test solution. With higher concentrations of auxin the growth of the segments in auxin-humate solutions was considerably greater than in solutions containing auxin alone. The effect decreased with rising concentrations of auxins (β-indoleacetic acid and α-naphthylacetic acid).
The auxinoid character of salts of humic acids in water solution was not established, nor was there any confirmation of competitive antagonism in the sense of the antiauxin conception.

1. In C. olitorius ♀ × C. sidoides ♂, the pod set was 29.4 per cent and the percentage of pod harvested (out of the set pods) was 20 per cent. All harvested pods were empty.
2. In C. sidoides ♀ × C. olitorius ♂, the pod set was 26.8 per cent and that 9.0 per of the cent pods were harvested. The single harvested pod yielded the following types of seeds-4 empty seeds, 9 partially full seeds and 4 apparently full seeds. The apparently full seeds were underweighed. All seeds were non-viable.
3. The pod sets in C. capsularis ♀ × C. sidoides ♂ and in its reciprocal were 31 per cent and 20.0 per cent respectively. No pod remained till maturity.
4. These three species are phylogenetically wide apart.

1. It was found that fluoride has a more pronounced inhibitory effect on the respiration of wheat leaves in plants grown in a solution of gibberellic acid than on that of control plants grown in water, during the entire development of the first leaf.
2. Respiration is markedly inhibited even in old leaves of gibberellintreated plants while the respiration of equally old control plants is stimulated by fluoride by 10-100%.
3. It is assumed that the shift in the equilibrium of respiratory pathways to glycolysis, as is indicated by respiration experiments, is associated with the growth effect of gibberellic acid.

During investigation of amylase activities as continuously variable biochemical features it was found that they are very sensitive to changes in the intensity of vegetative factors. The results of analysis of variance indicate that these characters not only tend to be inheritable themselves, but also the nature and intensity of their reactions to changes in the agro-ecological factors of the external environment show a similar tendency. The actual expression of these features in individuals belonging to a genetically homogeneous group must be considered as the resultant of all reactions of the realisation process concerned, on stimulatory and inhibitory influences, both internal and external. For the genetical analysis of hybrid groups it is necessary to have the most complete picture possible of this continuous modificability which masks the actual genetical variability.
The results obtained in the present investigation provide evidence of complicated relations involved in the hereditary nature and formation of the features under consideration. In further work on the later generations of reciprocal and back crosses it will be necessary to determine more exactly the relative participation of nuclear and plasmatic components both in the hereditary transmission and in the actual formation of these characters.
The present results, although they are only preliminary, confirm the correctness of the modern view in genetics that genetical analysis should be linked with physiological analysis.

Im vorliegenden Beitrag ist eine einfache Methode der Aufklatschchromatographie für die Bewertung des Zuckergehaltes in der Trockensubstanz der Aufklatsche (Aufklatschmasse) beschrieben. Diese Methode ist zum Zwecke der Verfolgung des Spiegels der einzelnen Zucker in den Wurzelspitzen des Weizens ausgearbeitet worden, der in Kulturen mit Humussäurezusatz bei verschiedener relativer Luftfeuchtigkeit wuchs. In der vorliegenden Arbeit ist er am Beispiel der Glukose, unter den Bedingungen niedriger, relativer Feuchtigkeit klargestellt worden. Der Glukosegehalt sinkt mit der Entwicklung der Pflanze bis zum Eintritt der Phase des zweiten Blattes. Während er in der Phase des ersten Blattes bei der Variante mit Humussäure grösser ist, ist dies in der Phase des zweiten Blattes bei den Kontrollpflanzen der Fall,

The part of the radioactive fractions of humus substances which is soluble in alcohol (or in ether) spreads from drops of solution or from a mixture with lanoline paste mainly through the vascular bundles. The active component of humic acid evidently does not spread in the leaves, while the active component of fulvic acids fails to penetrate the tissues of some plants, but in others spreads to a distance of several centimetres.

1. The classical cytological methods, cytochemistry and electron microscopy were used to study the cytoplasm ofFagopyrum esculentum Moench. 2. Cytochemical investigation of inclusions resembling the Golgi apparatus was possible after fixation in Ca-formaldehyde and embedding in carbowax. 3. A characteristic of the inclusions was drawn up. The inclusions resemble some pigment substances of animal cells cytochemically (lipopigments, phenolic pigments). 4. Conditions of staining inclusions with basic dyes, Sudan black B and the PAS reaction were studied. 5. A functional investigation revealed a cycle resembling that known in the formation of secretions in animal cells. 6. The Golgi apparatus and inclusions resembling it appear under the electron microscope as two distinct components.

On a traité des graines d'orge à différentes fréquences ultrasonores (30, 80, 570, 720, 960 kHz) avec des puissances de 2 à 5 W/cm², de 5 à 25 minutes, en vue d'étudier le mécanisme d'action des ultra-sons sur le processus de la germination.
A cet effet, nous avons effectué des enregistrements microcalorimétriques au laboratoire de Monsieur le ProfesseurE. Calvet à la Faculté des Sciences de Marseille, en vue de comparer les courbes représentant la cinétique de la thermogénèse dans le cas des graines traitées ou non traitées par les ultra-sons.
Les courbes montrent que la durée de la thermogénèse physico-chimique caractérisée par la première pointe exothermique est diminuée dans le cas des graines traitées et que le phénomène passe alors rapidement de la phase physico-chimique à la phase de thermogénèse biologique, la deuxième phase pouvant même se superposer à la phase physico-chimique.
Ainsi le traitement provoque une accélération de la germination et modifie favorablement la durée de celle-ci (thermogénèse biologique plus active). Le phénomène d'accélération de la germination se manifestant de la même manière sur des graines dont la thermogénèse fut étudiée plusieurs semaines et plusieurs mois après le traitement aux ultra-sons, cela montre que cette action est irréversible et correspond principalement à une modification de la perméabilité des membranes. Il est cependant possible qu'il vienne s'y associer des actions dépolymérisantes (Prat, Calvet 1945) (dépolymérisation de l'amidon en dextrine) qui expliqueraient, mieux que la seule absorption d'eau, la prolongation dans le temps de l'accélération de la croissance (diminution de la phase endothermique et accélération de la phase exothermique).
Ainsi la thermogénèse des graines traitées aux ultra-sons, grâce à la grande précision de la méthode microcalorimétrique, nous montre que la pénétration ultérieure de l'eau dans les graines, ainsi que les processus enzymologiques produisant la thermogénèse biologique, sont nettement accélérés par les ultra-sons.

1. The growth rate of apple pollen tubes at a temperature of 25°C in 10% sucrose solution, with or without boron (0.001% H₃BO₃), shows a practically linear relation to time for 6 hours;Nicotiana alata pollen tubes, which are slower in growth, show a decrease in growth rate after 10 to 15 hours.
2. The greater part of the sucrose in the culture solution is inverted by the pollen tubes. The rate of this reaction increases with time until the substrate is exhausted. When the sucrose concentration drops to 5%, chiefly as a result of the inversion process, the growth rate of the pollen tubes decreases.
3. The growing pollen tubes absorb sucrose from the culture solution. Exogenous utilization of sucrose was evident in the case of apple pollen after 3 hours, inNicotiana pollen after 6 to 8 hours of incubation.
4. In view of the close correspondence between the decrease in the intensity of sucrose absorption by the pollen tubes and the decrease in their growth rate, it may be concluded that the accumulation of callose in pollen tubes while their growth rate is decreasing is not due to any rise in the proportion of glucose not utilized for cell-wall formation. Further, if no change in the glucose: fructose ratio is observed in the culture solution at the time when pollen tube growth is slowed down, it follows that reduction in growth rate and increase in callose accumulation is most probably accompanied by a drop in respiration of glucopyranose component of the absorbed sucrose.
5. Boron encourages sucrose absorption proportionally to the stimulation of pollen tube growth. It is, therefore, possible that the stimulatory effect of boron on growth is connected with carbohydrate metabolism. In view of the fact that pollen tube growth is accelerated by boron at the time when the tubes are still drawing to a great extent or exclusively on the reserve substances in the pollen grain- and in view of the well-known stimulatory effect of boron in distilled water - it follows that the main factor is not necessarily the translocation of carbohydrates into the pollen tubes, but that it is rather a question of the rate of their metabolism.

The term "equivalent evaporation power" is suggested to denote the evaporation power of the atmosphere measured as the relative evaporation from an evaporimeter which resembles to a great extent the physical conditions occurring during transpiration of a plant leaf (e.g. the Piche evaporimeter).
The height dependence of equivalent evaporation power at heights between 5 and 500 cm. in an "open area", in a field of sugar beet, maize, in a mature deciduous wood, in its small circular rejuvenation clearing and on a great clearing was investigated. The higher the absolute values of evaporation the lower the height gradient which is obviously observed to decrease progressively with height in all cases (Figs. 1 and 2). The stands decrease the average equivalent evaporation power in the height interval exceeding their height. Differences between the relative values of equivalent evaporation power of atmospheric environment surrounding different leaves of one plant are frequently considerably higher than those between ecoclimatically completely distinct localities (e.g. between a forest stand and a clearing).
A statistically significant positive correlation was found to exist between the gravimetrically determined all-day total of transpiration of seedlings ofFagus silvatica L. andAcer platanoides L., freely exposed in small lysimeters for the entire vegetation season and between the all-day total of equivalent evaporation power. For the number of days n=95 the mean correlation coefficient r was +0.58±3.0.031 for the beech and +0.56±3.0.046 for the maple. The regression coefficient, which is linearly proportional to the leaf area, was low and provides evidence for the biological regulation of transpiration.
It was shown by simultaneous measurements of transpiration (gravimetrically) of leaves ofSyringa vulgaris L. (n=95) and of equivalent evaporation power at the height of 10, 50 and 150 cm. above the ground in an "open area" that the height gradient of equivalent evaporation power of the atmosphere under natural conditions affects the intensity of transpiration at different heights (Fig. 3).
The observed facts are undoubtedly to be associated with the formation of the xerophytic or mesophytic character of leaves located at different levels of the same plant, and thus withZalensky's law.

1. Die z. T. experimentelle Analyse des Blumenbesuches zweier Syrphiden-Arten (Tubifera pendula L., Syrphus balteatus Deg.) an Parnassia palustris L. unter besonderer Berücksichtigung von Tieren, die mit den Blüteneinrichtungen dieser Pflanze nicht vertraut waren, ergab, dass die "Scheinnektarien" der Blüten für die Fern- und Nahanlockung bedeutungslos und demnach für die Bestäubung entbehrlich sind.
2. Die vorliegenden Untersuchungen ergänzen meine frühere Analyse des Blumenbesuches der genannten zwei Syrphiden-Arten an Parnassia (Daumann, 1932, 1935), die unter vorwiegender Berücksichtigung von Tieren ausgeführt wurden, die mit den Blüteneinrichtungen dieser Pflanze bereits vertraut waren.
3. Meine Ergebnisse bestätigen nicht die AnsichtKuglers (1951), dass die "Scheinnektarien" von Parnassia palustris blumenbesuchende Fliegen "täuschen" und unter umständen die Besuchs- und Bestäubungsaussichten erhöhen können.

Für die Versuche haben wir die Maissorte Hodonínský koňský zub žlutý verwendet. Die vorgekeimten Getreidekörner wurden in fünf verschiedenen Dichten in die mit Sand gefüllten Mitscherlich-Gefässe ausgesäht. Jede Serie wurde fünfmal wiederholt. Die Maispflanzen wurden 21 Tage lang kultiviert. Es wurden Veränderungen des Wachstums, des Wassergehalts, der Katalase-und Peroxydase-Aktivität sowie der Atmungsintensität festgestellt.
Die Versuche erwiesen, dass sich unter dem Einflusse einer steigenden Bestandesdichte im Zusammenhang mit dem Gesamtwachstum auch die physiologischen Vorgänge innerhalb der Pflanzen wesentlich schwächten. Diese Prozesse wurden in den Wurzeln stärker als in den oberirdischen Teilen geschwächt. Unter allen beobachteten Vorgängen wurde die Wurzelatmung am stärksten herabgesetzt. Damit hängt wahrscheinlich auch die Herabsetzung der übrigen beobachteten physiologischen Funktionen zusammen, unter anderem auch die Herabsetzung der Mineralstoffaufnahme aus dem Boden, wie in der vorhergehenden Arbeit des Autors gezeigt worden ist (1959).

The authors have followed the free amino-acid relations in leaves of the apple variety Ontario, before and during the differentiation of flower buds. At the time when the flower buds were being differentiated on the fruitspurs, there was found to be an almost complete disappearance of arginine from the leaves. In the period before differentiation there was a temporary drop in the aspartic acid content and a temporary rise in γ-amino-butyric acid content; except for arginine, the over-all proportions of amino acids were preserved. It is not as yet possible to decide whether the above changes have any connection with the differentiation of flower buds. *** DIRECT SUPPORT *** A01GP005 00007

The effect of 17 pyrimidine derivatives on tobacco mosaic virus was tested in leaf disk cultures. The greatest antiviral effect was found with 2-amino-4-methyl-6-chloropyrimidine, which in a concentration of 500 μg./ml. caused a 98% inhibition of TMV multiplication. The structurally closely related 2-amino-4-methyl-6-hydroxypyrimidine gave a 77% inhibition. An equal concentration of uracil caused a 36% stimulation of TMV multiplication. Also the ethyl ester of S-(4-methyl-6-hydroxypyrimidyl-2)-thioglycolic acid had a 30% stimulatory effect. The following preparations were toxic in the concentration mentioned above: 2,6-dichloropyrimidine, 2,6-dichloro-4-methylpyrimidine, 2,4,6-trihydroxypyrimidine, 2-thio-4,6-dihydroxypyrimidine, 2,4-dichloropyrimidine, 2,4,6-trichloropyrimidine, and 2,6-dichloro-4-trichloromethylpyrimidine.

A technical procedure is described together with slight modifications and technical alternations, for the application of the quantitative serological method in work with labile plant proteins, particularly those from vegetative organs.
The procedure is based on the well-known method developed byBoyden et al., usingLibby's "photronreflectometer". The results published here have been obtained in the course of the determination of applicability of the following modifications to a quantitative evaluation of serological reactions:
a) The use of "acetone preparations" in obtaining antigens: A single operation is sufficient to remove undesirable admixtures, such as lipids, organic acids, tannin, alkaloids etc., the antigenic activity of the protein material being preserved. The conservability of such material in a dry state is considerably increased (for a number of months) by this procedure.
b) Stabilization of solutions of plant antigens of adding 5% fructose: The denaturation of plant proteins in frozen solutions is thus to a high degree prevented and their applicability is prolonged for a number of days.
c) A modification of incubation period and temperature during quantitative precipitation in order to ensure a more precise standardizing of the experimental conditions, with simultaneous decreasing of the antiserum doses.
d) Standardization of the calibrating process ofLibby's "photronreflectometer".
e) Application ofRunge's physiological solution; addition of ascorbic acid to prevent melanin formation in antigen extracts from plant material.

The inhibitory effect of mucin on infection with purified TMV in a mixture of the two components in the proportion of 1∶1 attains 76.8%. Mucin solution tested in the same proportion with infective juice reduces the infectivity of the mixture by only 20-35%. In human saliva compared with mucin as regards their inhibitory activity there is evidently another inhibitor at work, which does not exert an immediate inhibitory influence as in the case of mucin.
Urinary mucoprotein mixed with infective juice in the proportion of 1∶1 reduces infectivity by 78.7%. Infection with purified TMV is inhibited by it by almost 100%. All the results mentioned were statistically significant.
The present experiments have further followed the mutual relation between purified TMV, fresh juice from healthy tobacco and mucoprotein. The results show that the infectivity of the mixture of these substances depends on the order in which they are added. It follows from the experiments that mucoprotein also combines with an undefined substance in fresh tobacco juice.

The author describes a method for the determination of water deficit in disks punched out of leaves. The disks, 8 mm. in diameter, are placed on polyethylene rings and saturated in the apertures of a polyurethane foam plate which has been saturated with water (fig. 1, photo 1 and 2). This arrangement makes it possible for the tissue to be completely saturated in 3 hours with a minimum opportunity for infiltration.

Chicory blotch and yellows virus caused yellow local necrotic lesions on the leaves ofChenopodium Quinoa within nine days. Six strains of the common cucumber mosaic virus gave similar lesions in all cases, but in a shorter incubation period.

Chlorophyll formation in etiolated seedlings of wheat and maize, grown for 8 days on Knop's nutrient solution with 10μg. gibberellic acid (further GA) added per ml. was investigated and compared with control plants. Under the light of fluorescent tubes of an intensity of 3000 lux a significant decrease in the amount of chlorophyll (a+b) was observed at all time intervals from 0 to 24 hr., expressed both per dry weight and per leaf length. Experimental results indicate a decreased rate of chlorophyll formation in the presence of GA.
At the same time, a lower content of carotenoids was found in etiolated plants than in controls grown in absence of GA.
The colorimetric determination of the pigments was accompanied by paper chromatography which served as a control of quality and approximate amount of pigments.

Es wird über laufende Arbeiten berichtet.-Bei virösen Erkrankungen gehen dem Auftreten äusserlich erkennbarer Symptome cytologische Veränderungen voraus. Als solche werden u. a. charakteristische Zelleinschlüsse in jungen Keimen von Kartoffelknollen beschrieben. Mit ihrer Hilfe lässt sich nachweisen, dass viröse Prozesse auch in "gesund" getesteten Knollen vorkommen können.-Das unterschiedliche Auftreten spindelförmiger Zellkerne im Palisadenparenchym der Blätter von Solanum tuberosum wird als Zeichen verschieden stark ausgeprägter Neigung zu viröser Erkrankung (Virophilie) angesehen. Versuche zur chemisch-physikalischen Induktion viröser Prozesse ergaben ein bemerkenswertes Auftreten derartiger Kernformen in behandelten Pflanzen.-Die Virogenese wird als ein im Wesentlichen physiologischer Prozess aufgefasst, den die Pflanze gestaltet und der sich sowohl post infectionem als auch autonom entwickeln kann. Das anatomisch nachweisbare Vorkommen virogener Mikroprozesse und viröser Mikroherde macht den Nachweis, dass eine Pflanze virusfrei ist, unmöglich. Vielmehr ist mit der Ubiquität dieses Vorkommens zu rechnen.

From the partial results of artificial cultures in the presence of pistil tissue-pulp the author draws the preliminary conclusion that the inhibitory factor in the pistil ofNicotiana alataLink etOtto is already present before pollination.
These questions were investigated by means of artificial cultivation of pollen tubes on agar in the presence of compatible and incompatible pulped pistils which had been previously prepared in various ways.
This report gives the results of the last series of experiments (part A in the scheme). In the series of earlier experiments no signs of any marked inhibition were recorded.

The study of physico-chemical properties of protopectinase secreted by R. solani was for the first time made and recorded in this paper. The results can be summarised as follows.
1. Protopectinase preparation killed the cells even before maceration was completed.
2. Dilution with water and with autoclaved enzyme solution reduced macerating activity less than toxicity, and thus, indicated that toxins other than enzymes were present in culture filtrates.
3. Protopectinase was highly thermolabile as activity was completely lost after heating for 5 minutes at and above 60° C. When the enzyme was stored at 25° C. for 15 days, there was 80% loss of activity.
4. Protopectinase activity and toxicity was highest at pH 3-4 and there appeared another optimum at pH 7.4.
5. A slight loss of activity occurred on dialysis and was slightly restored by the addition of an autoclaved undialysed enzyme solution. Another peculiarity of the dialysed enzyme solution was that it was most active at pH 6.8 and less active at pH 3.5.
6. Protopectinase was more readily precipitated with acetone than with ethanol. The toxicity of the solution of the precipitate was less than what would have been expected. This again indicated that toxic substances, presumably not enzymic, were removed during the partial purification by precipitation.
7. The addition of monovalent and bivalent salts, particularly in high concentration, to the protopectinase solution resulted in some loss of activity; there was a greater loss with bivalent salts. But soaking test tissue in the salt solutions did not have any effect on protopectinase activity.

1. The aim of the present paper was an investigation of pollen grain size of different species of the Triticum L. natural polyploid series.
2. We determined the pollen grain size of 15 specimens belonging to 8 species. The determination was carried out on permanent acetocarmine preparations.
3. The pollen grain size of differentTriticum species tends to grow with the increasing number of chromosomes. The following mean volumes were computed for the different groups: 62.10³ μ ³ for the diploid group, 96.10³ μ ³ for the tetraploid group (of which 73.10³ μ ³ forT. timopheevi Zhuk.), and 118.10³ μ ³ for the hexaploid group.
4. As can be seen, the volume of the pollen grain does not represent a corresponding multiple of the chromosome number. The reason for this disagreement with the theoretically expected linear relation between the chromosome number and the pollen grain size lies apparently in the allopolyploidy of the polyploid series of the genusTriticum. It seems that the genetically different genoms A, B, D, and G also exert a different effect on the pollen grain size.
5. Our calculations show genom B to have 62%, genom D 29%, and genom G 18% of the effect of genom A (100%). These genoms form a sequence A>B>D>G with respect to their effect on pollen grain volume.

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.

Weder die Dominanzverhältnisse zwischen den Sprossanlagen noch die Regulationswirkungen der Laub- und Keimblätter, die unter anderem für die vorzeitige Wachstumssistierung namentlich bei den Holzgewächsen verantwortlich sind, lassen sich durch Gibberellinsäure verändern. Doch setzt GS die von assimilierenden Blättern und vegetativen Speicherorganen ausgehenden Hemmungen herab und ersetzt in dieser Hinsicht die Stimulationswirkungen der Wurzeln, allerdings nur unvollständig, da es nachher zu den bekannten Ernährungs- und Gestaltungsstörungen kommt. Auf die Knollenbildung wirkt GS ungünstig, da die Terminalknospe der Knollenanlage zu starkem Streckungswachstum statt zu erforderlicher Ruhe gebracht wird. Die günstige Wirkung von GS auf die Blütenbildung bei der LangkurztagpflanzeBryophyllum crenatum tritt nur dann ein, wenn die mit GS behandelten Kurztagrosetten noch weiter im Kurztag gezogen werden. Somit kommt es hier mehr auf die phylogenetische Anpassung dieser Pflanzen an die Tropen, als auf gewisse stoffliche Einflüsse an, was mutatis mutandis auch von der Rhythmik der Bäume gilt. *** DIRECT SUPPORT *** A01GP005 00005

A description is given of the production of two types of chimera between tomato and nightshade (Solanum koelreuterianum Winkler andS. geartnerianum Winkler).
In the case ofS. gaertnerianum the micromorphological and anatomical characters showed no signs of the significant specific reciprocal effect of one tissue on the other.
The seed progeny of theS. gaertnerianum chimera resembled the control nightshade plants in all the characters investigated.
The following characters were studied: Size of stomata, shape of stomata, shape of trichomes, fruit epidermis, section through the petiole, section through the leaf blade and number of seeds.

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.