Two techniques recently described for the demonstration of protein SH in animal material were appllied to plant objects in this work: the technique with β-oxynaphthylmercurichloride and that with p-nitrobromacetophenone. These techniques together with DDD¹ and RSR¹ usually produced more intense staining in plant cell nuclei than in the cytoplasm. When reactions for protein carboxyls and tyrosine were used, similar differences in the intensity of staining the nuclei and cytoplasm were observed. It appears that the differences in the intensity of reactions for protein SH groups correspond to the differences in the concentration of total protein in plant meristematic cell nuclei and cytoplasm.

Leaf cells of healthy cucumber and cucumber infected with Cucumber virus 4 were studied living and fixed, using optical and electron microscopy. Under the electron microscope the infected leaves displayed changes in the structure of the ergastoplasm, Golgi apparatus, mitochondria, bodies with an osmiophil matrix and chloroplasts. The chloroplasts exhibit symptoms of fatty degeneration which affects above all the lamellar systems of grana and intergrana. Weakly osmiophil globules, abundant in damaged chloroplasts, are probably formed through degeneration of grana. Chloroplasts of infected plants resemble some transitional stages of plastids observed during chromoplast formation. The problems of localization of viruses in the cell and degeneration are discussed.

Auf Grund morphologischer Versuche mit Syringa vulgaris, Ligustrum ovalifolium, Philadelphus coronarius, Aesculus hippocastanum, Acer negundo und Bryophyllum crenatum wurde in dieser Arbeit die Abhängigkeit der Erhaltung entspreiteter Blattstiele von den korrelativen Einflüssen anderer Teile der Pflanze untersucht und die Möglichkeit der Nachahmung dieser Korrelationen mittels synthetischer Wuchsstoffe geprüft. Es zeigte sich, dass die Ganzheit der Pflanze, die vor allem durch die Regulationswirkungen der Wurzeln und Blätter bedingt ist, aus dem Verhalten der entspreiteten Stiele klarer hervorgeht als aus dem der ganzen Blätter. Dabei kommen Kompensationen, Polaritätsverhältnisse und embryonale Determinationen zur Geltung.

It was the objective of the present communication to establish the effect of short-term aeration with air alone or air enriched with 5% carbon dioxide on growth and oxidative metabolism of Chlorella pyrenoidosa. An organic medium was used to permit the investigation of the effect of aeration (one hour a day) both under illumination and in continual darkness.
Short-term aeration with air either alone or enriched with carbon dioxide increases dry-weight production both in the light and darkness. We are thus not dealing here with a mere effect on photosynthesis. This treatment affects the oxidative metabolism of the alga: oxygen uptake was always higher in those cultures which were more aerobic during cultivation (aerated cultures in the dark and non-aerated, or only with pure air cultures in light). Cultures in the individual variants display different endogenous respiration when measured manometrically.

The buds remowed from the fruit-bearing cluster bases of trees with fruit had a higher concentration of free asparagine and of some free amino-acids than the buds taken from trees without fruit. The quantitative relationship between amino acids in the hydrolyzates of the buds from the trees with and without fruit was very similar.

The sequence of intensities with which pollen tubes utilize tested sugars from their 0.3 M solutions, is the following: sucrose >glucose >invert sugar > >fructose. The same sequence is maintained in sugar-agar media with the exception of the first two hours of incubation when sucrose, glucose and fructose are all utilized at a practically equal rate. During this period no pollen tubes were formed in the presence of fructose, in common with the sugar-free control, while in the presence of sucrose they reached a length of up to 450 µ. If sucrose was used as carrier for radioactive sugars, fructose-¹⁴C was utilized up to 12 times and glucose-¹⁴C as much as 6 times more actively than sucrose-¹⁴C. When sucrose + glucose or sucrose + fructose (in molar ratio 1 : 1) were used the pollen tubes utilized sucrose-¹⁴C at a slower rate than the corresponding monosaccharide and also at a slower rate than observed with sucrose alone. When glucose or fructose was used as carrier for sucrose-¹⁴C . the carbon dioxide-¹⁴C production by the pollen tubes was (during several time intervals of the experiment) several tens per cent higher than when sucrose served as carrier. Fructose is utilized preferentially from a medium with invert sugar.
It thus appears that the capacity of the pollen enzymic systems for incorporating the sugars tested into their respiratory pathways is as follows: fructose >glucose > sucrose, this sequence being the opposite to that found for the intensity of their growth effect and to that established for the rate of their utilization, unless present in combination. The specific growth effect of sucrose cannot thus be due primarily to the rate of its absorption or to the intensty of its utilization. The rapid rate of utilization of sucrose alone is due to the more intense growth in the presence of sucrose. The results obtained further suggest that sucrose is utilized above all via its inversion when the fructose component is respired preferentially.

From photoperiodic experiments and an anatomic study of the shoot apex in the facultative short-day plantsPerilla ocimoides L. it was shown in all cases that gibberellic acid (GA) application did not accelerate flower induction. Between the development grades 2 and 4, GA caused a certain temporary acceleration which, however, completely equalised in a short period and plants of both variants SD and SD+GA flowered at the same time. Long day plants (LDand LD+GA) also flowered simultaneously with a certain delay. GA caused the total length of the plant to increase in both cases by more than a double, while preserving practically the same number of leaf pairs in variants under the same photoperiodic regime.

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.

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.