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.

Po inhibici jarovizace azidem sodnym byla u ozimé pšenice sle dována délka čepele prvního listu. Srovnáním různych variant a jamí odrůdy se ukázalo, že zkrácení délky čepele prvního listu nemá přímý vztah k jarovizaci.

The author carried out a cytological evaluation of 40 varieties of the basic Czechoslovak assortment of pears. Thirty of these were diploid and ten were diploid.
In addition to the chromosome number of these varieties, he determined the average dimension of the leaf stomata, to prove that it is possible to use this method in pear trees to make a reliable differentiation between diploid and triploid varieties. From a determination of the average lengths of the stomata it follows that the diploid varieties of pears can be distinguished from the triploid varieties by means of this criterion.
A further, very accurate mark of difference between diploid and triploid varieties, is the lagging of chromosomes in the spindle during the anaphase of the heterotypical division.
In the various varieties a divergent susceptibility to staining of the tissues was found which is not dependent on the method of microtechnical processing but in the first place, on the properties of each individual variety.
Regarding the statements of Darlington and Moffet on the one hand and Sax's objections on the other, the author's cytological findings in the case of triploid varieties are in agreement with those of Sax and also with his opinion on the debatableness of polyvalent associations found by Darlington and Moffet.

1. Le cicadineCalligypona pellucida FABR. est très vraisemblablement le vecteur des souches européennes de la jaunisse à virus des asters, les transmettant sur le poireau et l'oignon; cette maladie se manifeste surtout par la prolifération de 1'inflorescence.
2. Cette maladie n'était pas transmise par greffage des secteurs du bulbe du poireau atteint sur les bulbes de poireaux sains. On en peut donc conclure que le virus n'est pas présent dans le bulbe, ou qu'il n'y est qu'en quantité très petite, ou encore qu'il ne peut persister en état actif.
3. Le rapport entre les poireaux proliférés et les fleurs en l'inflorescence des plantes malades est variable, et il prouve ainsi la variabilité du niveau des virus dans l'inflorescence même.
4. Chez les plantes malades il n'y a que peu de graines qui se développent, et leur capacité de germination est faible.
5. Les expériences citées prouvent de nouveau tant l'acropétalité que la variabilité du niveau des virus dans les parties individuelles des plantes.

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.

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.

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.

In addition to the oat sterile-dwarf virus (OSDV) as the main agent causing grave damage to cereal crops in the Bohemian-Moravian Highlands during 1954-56, when the disease reached catastrophic proportions, it was found that wheat striate virus (WSV) also played a part. Symptomatological study showed that there are characteristic differences between the effect of WSV on the host plants and that of OSDV. Similarly to OSDV, however, WSV is specifically spread by the leafhopperCalligypona pellucida Fabr. Following long-term individual testing of vectors taken from localities infested with OSDV and WSV, four groups of insects were distinguished according to their pathogenic effects on cereal crops: 1. nonpathogenic, 2. producing OSDV symptoms, 3. producing WSV symptoms, 4. producing for the most part OSDV symptoms, but occasionally WSV or symptoms characteristic for both viruses simultaneously. WSV is persistent in its vector and is transferred byC. pellucida larvae at different stages of development and by imagos of both sexes. WSV tends to be transferred less regularly than OSDV. Considerable differences in efficiency of carrying WSV are to be found between individual leafhoppers, so that it is possible to assume the existence of races with varying efficiency in this respect. Among field populations in this country less efficient races prevail. For the transmission of WSV to be effected it was necessary for the vector to remain on the host for at least nine hours, but it seems that a shorter period might suffice. Extracts of crushed leaves of wheat plants suffering from the striate disease and from infective leafhoppers failed to cause infection when inoculated mechanically (by rubbing, injection) into plants. Attempts to achieve transmission through the soil or by dodder (Cuscuta campestris Yunck.) gave negative results. It was not possible to determine the thermal inactivation point of the virus in the live vector. The mosaic (zakuklivanie) virus of oat and the Russian mosaic of winter wheat as described in the U.S.S.R. differ from OSDV and WSV among other points by the production of typical inclusions and by the fact that they can easily be induced to crystallize.

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.