Proof is given in this paper that dwarfing of wheat, which occurs in several regions of Czechoslovakia, is a virus infection. The virus was transmitted by means of naturally infected imagos of the leaf-hopperPsammotettix alienus DAHLB. to spring wheat and spring barley. It was also found that it is transmissible to a high degree by larvae grown from eggs which are then artificially infected at the source of infection. An attempt to transmit the virus by means of the aphidsBhopalosiphon oxycanthae (SCHRANK.) andSitobium granarium (KIRBY) MORDV. was negative. Nor was it possible to transmit it by soil, wheat grains or by mechanical inoculation with sap from diseased plants.
The Russian mosaic virus of winter wheat would seem, in view of its vector, to be the most closely related to the wheat dwarf virus. It differs, however as regards the symptoms produced on the host cereals, by having a different vector and by the absence of inclusions in the cytoplasm of infected plants. These facts indicate that we are probably dealing with a new virus, which has not previously been described.

In a hybridisation experiment, the hereditary fixation of mutations of a branched form of rye, characterized by an enlargēd number of blossoms and inflorescence parts, was studied. It was found that the hereditary fixation of this form was monomerily recessive with respect to the rye sort Dobřenická trsnatá, the spike formation being normal. It was also shown that neither particularly good nor particularly bad soil conditions had any effect on the split ratio of 3 : 1 in the F₂ generation. The mutation form studied was stable within a very wide interval of soil and climatic conditions. We are probably dealing here with a stable disturbance in the morphogenetic process resulting in spike formation.

Antagonism of three saprophytes to the pathogen,Rhizoctonia solani was studied in plate cultures under different conditions of temperature, pH, and nutrition. The antagonistsTrichoderma viride andChaetomium cochlioides were found more effective in the inhibition of the growth ofR. solani at temperatures 25 and 20° and this conforms to their growth-temperature relationship.T. viride was found more effective in acid media as reported by others, whereas other antagonists and especiallyC. cochlioides was more effective in the alkaline medium. Hence the suggestion is made that soil amendments increasing the activity ofC. cochlioides might be a good control measure against the pathogen in alkaline soils.
The most interesting result of the investigation is that, contrary to the previous reports,R. solani appeared to be more cellulolytic thanT. viride andC. cochlioides and this result was unaffected by the use of NH₄C1 as N-source.

The author investigated in the course of two years the osmotic pressure of 70 trees of 7 apple tree sorts, 5 of these bearing fruit periodically and 2 every year. At the beginning of the experiment, one half of the trees were without fruit and the other half with fruit-set. The experiment was carried out on 10-12-year-old trees (stock M II, M IX and M IV) in the NW apple-growing region of Bohemia (Střčžovice, Těchobuzice). Three or four times during every vegetation season leaves of brachyblasts of fruit-bearing and resting apple trees were removed and the osmotic pressure of their cell sap as well as its electric conductivity were measured. Once in every season, terminal buds of brachyblasts usually giving rise to flower buds were removed and treated identically as the leaves.
It follows from the data obtained that growing fruits bring about a decrease in osmotic pressure of leaves of apple trees by 2-6 atmospheres, depending on the amount of fruit-set and on the season. This decrease depends very little on weather and differences in osmotic pressure of the cell sap of fruit-bearing and resting apple trees are highly significant in July. The cell sap osmotic pressure in buds is decreased less - by 1-2 atmospheres. A significant positive correlation between the value of osmotic pressure and flöwer-bud formation of the sort Boskopská červená was demonstrated. In sorts bearing fruit annually, no such correlation, could be observed.

Kinetin and 6-benzylaminopurine were applied to apple-trees (Malus domestica) with the aim of regulating growth and metabolism of buds. A single dose of 20-200;Cg. kinin counteracted the inhibitory effect of the fruit on bud growth. Lower doses resulted in thickening of buds, higher doses in bursting of buds to form twigs.
It was found with the aid of radioactive phosphate that the inhibitory effect of fruits is reflected particularly in a considerable decrease of incorporation of radioactive phosphate into the fraction of free nucleotides, especially in meristematic tissues. Furthermore the rate of synthesis of nucleoproteins and phospholipids is considerably decreased in the buds of a fruit-bearing apple-tree as compared with those of one which is barren in the given year.
The kinins bring about a change in the metabolism of buds adjacent to fruits (both of their meristem and scale integuments) and the incorporation of radioactive phosphate resembles after a seven-day exposure very much that in the buds of a barren apple-tree.
Radioactive 6-benzylaminopurine-^9-14C was synthesized here and autoradiography revealed that it is localized in the vicinity of the point of application, predominantly in the bark and in the phloem. It is little transported toward the apical end, somewhat more toward the basal end of the shoot (an X-ray film darkens several cm. away from the point of application). After an extended period of time another radioactive substance was isolated from the experimental material, the substance differring from 6-benzylaminopurine in itsRF value during paper chromatography. The substance is being further investigated.

A modification of the leaf-disk method of BARTOš, KUBíN and ŠETLíK (1960) is described for use in studying photosynthesis in cereals. In place of leaf-disks segments of 2 cm. in length are used. Two segments are cut by a punch from each leaf, one segment serving for the determination of dry weight at the beginning of the experiment, the second being exposed in a chamber under constant conditions. In view of the heterogeneity of the leaf, two segments from the opposite parts of the leaf must be used for each sample. A suitably modified support is also described for holding the segments in order to ensure their saturation with water. Dry weight increments of first-leaf segments of two sorts of winter wheat grown in sand cultures under artificial illumination are presented. The dry weight increment is linear in the course of 12 hours and with the sort Weibulls Banco it amounts to 51.5% which corresponds to an increment of 122.5 mg./dm.².

As the species hybridSalvia němecii (= S. nutans x S. jurišićii) is highly fertile, genetic analysis of the segregating F2 generation has been carried out. In 238 plants of F2 the following leaf characters were investigated: type of the vascular bundle course in the petiole, the ratio of the petiole to leaf blade length, the ratio of the length of the leaf blade to the breadth, and the segmentation of the leaves, i.e. ratio between an ideal contour surface and the actual surface of the leaf blade. All these characteristics were compared with those of the original parental species as well as of the F1 generation. It was found that:
1. Type II of vascular bundle course has simple dominance over type III (segregating ratiol72 : 66, X²(1) = 0.94, P = 0.35).
2. All morphological characteristics of the leaves behave as though governed by polygenic systems. The segregation in F₂ is always very wide and the extreme segregants exceed the values present in both parental species.
3. The type of vascular bundle course in the petiole is inherited independently of the morphological signs of the leaves. There is practically no correlation between vascular bundle type and any of the morphological ratio indices.
4. Between the morphological characters, on the other hand, there are significant correlations, especially between the length of the petiole and segmentation of the leaf (r = 0.31), and between the segmentation and the length-breadth ratio (r = -0.42). Therefore, some of the polygenes concerned may be linked together, i.e. localized in the same chromosome, but most of them are transferred independently.

The extent of material that had to be examined in the cytological evaluation of 40 varieties of the Czechoslovak basic assortment of pears made it necessary to work out a new, rapid method of investigation.
This method makes it possible to obtain permanent sections from about 1800 anthers within three days. During the first day, a total of three series can be imbedded in paraffin wax and each of these may contain about 600 anthers. There is sufficient time during the second day to section the three series and place the sections in gallocyanin where they are left overnight. On the following day, the sections containing about 1800 anthers are imbedded in Canadian balsam.
This method can be used with all plants having anthers sufficiently large for extirpation during the period of cell-division in the pollen mother-cells.

Seven strains of the clover phyllody virus originating from different localities in Slovakia were transmitted by means of the leafhopperEuscelis plebejus (Fallen) toTrifolium repens L.,T. pratense L.,T. hybridum L.,Senecio vulgaris L.,Taraxacum officinale WEB.,Chrysanthemum carinatum SCHOUSB.,Vinca rosea L. andThlaspi arvense L. Thus the ability ofE. plebejus to transmit the clover phyllody virus occurring in Slovakia was confirmed. The incubation (latent) period of virus in the vector lasted about a month and the percentage of leafhoppers which became viruliferous amounted to 30-60%. The importance of susceptible weeds in the circulation of the clover phyllody virus in nature is pointed out and the symptoms of disease caused by the individual virus strains in the plants tested are described.

Při pěstování rostlin kukuřice ve sterilních kulturách je třeba obilky desinfi-kovat, aby se zniěily zárodky mikroorganismů. To snižuje jejich klíčivost, zpozdí růst a tvorbu chlorofylu během prvních několika týdnů vyvoje klíčních rost-linek. Nejde o specfflcké inhibice, nýbrž o vývojové opoždění neprojevující se ani v poměru dlouživého růstu a hromadění suŠiny. Opoždění je nejvě tší při po-užití roztoku sublimáta nebo ethanolu. Vhodnější je desinfekce roztokem chlor-aminu. Změny vyvolané tříhodinovým namáčením jsou vyrovnány během cca 3 tydnů, bězně užívaná sedmihodinová desinfekce vyvolává kromě silného sní-zeni klíčivosti (téměř ? 50 %) déle trvající, avšak nezásadní změny. Chloramin neovlivnil tvorbu pohlavních organů, intensità fotosynthesy byla úměrná množství chlorofylu. Desinfekce chloraminem lze tedy užít, aniž by se rostliny podstatně lišily od těch, které byly vypěstovány ze suchých obilek.

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.

The levels of l-ascorbic acid, dehydroascorbic acid and of the bound form of vitamin C were investigated in the tissue from the vicinity of eyelets of dormant potatoes after treating the tubers with ethylene chlorhydrin. During the first week after exposure the l-ascorbic acid level does not change, significantly while the dehydroascorbic acid level decreases markedly. This decrease persists even during the following weeks and returns to normal only on the fourth week after treatment. The l-ascorbic acid level displays a decreasing tendency but a marked decrease may be observed only during the fourth experimental week. The level of the bound form of vitamin C does not change significantly for the whole duration of the experiment.
It can be concluded on the basis of the results obtained that ethylene chlorhydrin deeply affects the oxidation-reduction systems of the potato cell, among other possibilities by disturbing the equilibrium of the important oxidation-reduction system formed by l-ascorbic and dehydroascorbic acid. The bound form of vitamin C does not appear to play a significant role in the process of sprouting.

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 persistent nature of oat sterile-dwarf virus (OSDV) and wheat striate virus (WSV) has also been examined in an experiment using larvae of the vectorCalligypona pellucida Fabr. These larvae were grown from eggs under conditions excluding the possibility of their contamination by feeding on virus-infected plants. The eggs were from females of a population in which preliminary tests had shown that 14.4% of the individuals were non-infected, 61.2% infected with OSDV, 1.9% infected with WSV and 22.5% infected with OSDV and WSV simultaneously. Several months of individual examination of the infectivity of control larvae, which had never had the opportunity to feed on virus-infected plants, showed that none of them transmitted OSDV, although their parents were infected with it to a high degree (83.7%). On the other hand, 14.9% of the insects transmitted WSV, with which their parents were infected to a lesser degree (24.4%). Thus the larvae concerned must have acquired WSV transovarially from the female parents, and this must have taken place in a high proportion of cases. This remarkable characteristic enabled WSV to be separated from OSDV, with which it often occurs in Czechoslovakia. Larvae which went through acquisition feeding on WSV-infected oats showed, as compared with the control, a 61.6% increase of infectivity after a period corresponding to 26 to 34 days' circulation period of the virus in the vector's body and an increase of 98.2% after a circulation period lasting 40 to 51 days. Evidently mutual antagonism between OSDV and WSV in the body of the vector does not arise, since the infection of a leafhopper with one virus does not seem to prevent its infection with the other. Cross protection between OSDV and WSV in the host cereals either does not exist or is quite insignificant, because the hosts can suffer from both viruses at the same time. However, the symptoms of one virus can be masked to a varying degree by the symptoms of the other.

The authers compared taxon and organ specificity of proteins of several species of the familyViciaceae, using qantitative serological methods. Each organ possesses a defined organ specificity of protein characters, the species specificity being preserved. On the basis of the results obtained both methodical and more detailed ontogenic and phylogenetic assumptions and conclusions could be drawn.