The dense vacuoles, considered to be the classic Golgi apparatus in the root meristem ofFagopyrum, were studied by the following methods: 1. Impregnation methods for the demonstration of the Golgi apparatus, 2. cytochemical methods, 3. electron microscopic methods in the light microscope and 4. the electron microscope. A comparison was made with the classic Golgi apparatus in animal cells in the light and electron microscope.
Dense vacuoles inFagopyrum and also evidently in other plants, were taken for the classic Golgi apparatus on account of their morphological similarity to the Golgi apparatus in animal cells on impregnation with silver and osmium and their staining preperties with lipoid methods. Dense vacuoles differ from the classic Golgi apparatus in other chemical properties, such as content of phenol substances, etc. No formations were found in animal cells which were similar to dense vacuoles on investigating by electron microscopy. In the electron microscope dense vacuoles have the appearance of derivatives of the normal light vacuoles known in plant cells. They therefore belong to vacuome of plant cell and cannot be analogous to the classic Golgi apparatus in animal cells. Thus the use of the term Golgi apparatus for dense vacuoles is not well founded.
A comparison was made of fixation and impregnation used in the light microscope with fixation in the electron microscope. After fixation with permanganate, dense vacuoles have the same shape as after impregnation. After fixation with permanganate, they stain an intense black in the same way as after impregnation with silver and osmium. The form of the vacuoles is dependent on the fixation used. The comparison was made in the light microscope.

In field experiments, potato varieties with different lengths of the vegetation period were compared. The methods of growth analysis were applied to the evaluation of these experiments. Some important specific features of potato growth had to be taken into account to make the application of the growth analysis successful and to enable valid and reliable results to be obtained.

Many studies have been made on ribosomes both in plant and animal material, on account of their importance in the proteosynthesis of protein. In plant material, studies have been made on the pea by Ts'o andBonner (1956), Ts'o,Bonner andVinograd (1958),Setterfield et al. (1960) andSisakyan et al. (1963). Ribosome from spinach were investigated byLyttleton (1962) andMurakami (1963) and fromClivia byMikulská et al. (1962). As part of a wider study of the mechanism of biosynthesis of nucleic acids in apple trees, we isolated ribosomes from the young green fruit and studied them by means of electron microscopy. Young apples were selected because cell division is very intense at this stage of growth of the apple.

An investigation was carried out on ability of Ypenyl,i.e. 5-bis-(2-chloroethyl)-aminomethyluracil to induce structural disturbances of chromosomes and changes of mitotic activity of meristematic cells ofVicia faba. The cytostatic employed induced chromosomal aberrations mostly of the chromatide type, the greater part of which were localized in the group of small chromosomes. The frequency of aberrations was proportional to the concentration of the substance used as well as to the duration of treatment. After a 24 hour treatment with 0.01mm solution of Ypenyl the maximum incidence of aberrations was found after 8 hour recovery in water. Longer recovery periods resulted in a gradual decrease in the number of aberrant post-metaphases in the cell population studied. Increasing concentration of Ypenyl led to the decrease in mitotic activity. Short recovery periods caused a considerable decrease in the mitotic index, which was compensated as late as 16 hours after treatment with the cytostatic.

Three protein fractions (albumins, globulins and glutelins) of cotyledons of ripe and dormant soybean seeds were analysed by a modified polyacrylamide disc electrophoresis method. All fractions were shown to be multicomponent and easily characterized by their "protein electrophoresis spectra". A method of characterizing proteins by their relative electrophoretic mobility (R.E.M.) by comparison with a new nontoxic dye as a tracer is employed for a preliminary identification of proteins. Specificity of protein complement was investigated in view of the autors, further studies on dynamics of specific proteins in the course of ripening and germination of soybean seeds.

Sugar beet mosaic virus (SBMV) was precipitated by polyethyleneglycol (PEG) 6000 from the cell sap of infected sugar beet leaves. After centrifugation and addition of dextrane T 10 the virus was lyophilized. Its infectious activity was demonstrated by mechanical transmission toChenopodium quinoa Willd. and to sugar beet. Stability of infectious activity of the lyophilized virus was verified.

Influence on individual types (fractions) of nucleic acids (NA) was studied in roots of wheat plants grown in various cultivation media, namely in distilled water, in sodium humate and in a nutrient solution. NA's were prepared by means of the phenol technique. Using separation on a methylalbumine column (MAK) five fractions were obtained, namely: fraction I.- low molecular weight substances, fraction II.-soluble RNA, fraction III.-DNA-RNA, and the ribosomal RNA in two fractions, IV.-(l r-RNA) and V.-(h r-RNA). Of the NA fractions investigated, the r-RNA fraction was noticeably influenced by the kind of nutrition, its amount varying in a certain proportion to the growth intensity affected by the cultivation medium. The other NA fractions were not apparently affected.
The metabolical turnover of the individual NA types (as observed from the specific³²P activity) was considerably influenced by the kind of nutrition as well. The specific³²P activity in all NA fractions of wheat roots cultivated in a nutrient solution was approximately double that in roots of wheat plants cultivated in distilled water and Na-humate.
Changes in the specific³²P activity of r-RNA were again considerably evident. With regard to root growth their relative values appeared in an inverse proportion to the changes in the r-RNA content. The specific³²P activity decreased with increasing growth intensity.
Besides changes in the r-RNA fraction, changes in fraction I. were apparent. An especially striking decrease in the specific³²P activity was found in roots of plants grown in H₂O, namely by about one order in comparison with its specific activity in fraction I. from roots of plants grown in Na-humate and in a nutrient solution.

Carbamide and thiocarbamide decreased the resistance of apple to apple scab when infiltrated into apple leaves prior to infection with the disease. In three apple varieties these two substances strikingly stimulated infection with two monosporic isolates of the fungusVenturia inaequalis (Cke.) Wint. It was established that both carbamide and thiocarbamide inhibited polyphenol oxidase activity in apple leavesin vivo, butin vitro only thiocarbamide was inhibitory. It can be concluded that the effect on apple resistance to apple scab is based on an inhibition of polyphenol oxidase.

In dialyzed extracts from winter wheat plants transamination reactions occurred between asparagine and α-ketoglutaric acid (L-asparagine+2-oxoacid=2-oxosuccinamate+ +amino acid; 2. 6. 1. 14). Reactions with pyruvate exhibited a very low activity. Besides transamination products,i. e. glutamate and alanine, aspartic acid was formed in both reactions. Deamidation was more intensive in the weak reaction asparagine-alanine and less intensive in the asparagine-glutamate reaction.
When calculated per dry weight unit the activity was the same in plants of all variants (three experimental variants-Knop, potassium humate, water). A higher, activity was found in root dialysates; however, a highly significant difference could be observed only between shoots and roots of Knop variant. When evaluating results in terms of protein content we found a significant difference between mineral variant (Knop-the lowest activity) and both deficient variants (potassium humate, water-the highest activity). Thus the highest growth activity was in connection with the lowest transamination activity and vice versa, which was the same as in transaminations of aspartic acid. In the case of asparagine, too, one can consider the possibility of its utilization via transamination for biosynthesis of glutamic acid in plants which have, for reasons of nutrition, a low level of this metabolically important amino acid.

A virus having 300 nm long rod-shaped particles was isolated fromPlantago media L. in Yugoslavia. The virus was transmitted to 15 species of host plants the symptoms of which are described in detail. The symptoms corresponded to those that appeared after infection by the original Holmes' ribgrass virus (HRV).
The investigated virus was compared both with the common strain of tobacco mosaic and the original Holmes' ribgrass viruses by means of serological tests. The agar double-diffusion tests showed that it is closely related to HRV and remotely related to the common strain of TMV. On the basis of these results we concluded that this virus represented a strain of the HRV.
The investigations of the cell inclusions showed that our virus produced rounded plates instead of hexagonal prisms. Electron micrographs of ultrathin sectioned material demonstrated that these plates were formed by virus particles lying perpendicularly to the layers of the plates. The presence of plates also points to the fact that the investigated virus belongs to the HRV.

A new mathematical model, representing the transpiration process during ontogenesis and a circadian transpiration cycle, analysed in detail statistically, was designed using data obtained by the new modification of the gravimetric determination of the transpiration of intact plants. Regression analysis applied to the circadian cycle makes it possible to characterize basis parameters of the intensity and of the extent of this process and may serve as a starting point when studying transpiration methodologically in greater detail.

Beet yellows virus (BYV) was mechanically transmitted by sap from sugar-beet plants, infected with BYV, to the plants of Chenopodium quinoa Willd. and of Chenopodium foliosum (Moench) Asch. Mechanical transmission of BYV to the plants of Tetragonia expansa Murr. failed. Infectious material was homogenized in phosphate buffer with veronal and EDTA, pH 7-8. Experimental plants were darkened three days before infection and kept at a temperature of 5°C. Plants of C. quinoa Willd. were decapitated. Back transmissions from C. quinoa Willd. and C. foliosum (Moench) Asch. infected with BYV, to sugar-beet plants were carried out by the aveid Myzus persicae Sulz. These transmissions were positive. Filamentous particles of BYV, of an average length 1275 nm, were found in plants of C. quinoa Willd. and C. Foliosum (Moench) Asch., infected with BYV.

The virus origin of a Czechoslovak isolate of potato witches' broom disease is discounted: electron micrographs of ultrathin section of phloem tissues from plants infected with potato witches' broom disease demonstratedMycoplasma-like bodies, spherical or elongated showing binary fission and fragmentation. The minute corpuscles have a diameter of about 50-60 nm, the largest bodies of 1000 nm. The width of elongated filamentous structures is about 200 nm, most oval bodies have a diameter of 250 nm. A weak tetracycline treatment of diseased plants causes a delay of symptom development; a strong dose of tetracycline (applied by means of the wick method into the stem) inhibits symptom appearance completely. Tetracycline produces a phytotoxic effect inhibiting the growth of tomato plants and causing (at higher concentrations) necrosis and death of these plants. There is a note in the paper dealing with the term "mycoplasma". The word mycoplasma in the sense ofEriksson (1897) or ofMereschkowsky (1910) does not correspond to the genus nameMycoplasma Nowak (1929).

The time course of fertilization in barley is described and the observations compared with those of older authors. The triple fusion is terminated in spite of its late onset always before syngamy. Whereas the time period reported for the so-called preparatory phase of fertilization and for the division of the primary endospernal nucleus is similarly reported by many authors, there are difference of as much as 8 hours in various report on the beginning of the division of the zygote (beginning of the prophase 13-21 hours after fertilization). In the present material, the zygote began to divide latest.
The transient reserve substance representing an energy store for fertilization in barley was found to be starch. Barley belongs to the species in whcih starch is formed in the pollen grain and the pollen tube itself. When the content of the pollen tube is released, part of it arrives in the embryo sac. A mature embryo sac contains many starch grains near the nucleus of the oosphere and the polar nuclei. Gradual hydrolysis of this starch is related to the more rapid triple fusion and the slower syngamy.

The effects of low doses of two mutagens (UV-light and ethyl methansulphonate) on the growth of algae on a solid minimal (anorganic) medium were studied. It was supposed that low doses of mutagens will be more suitable for the induction of growth mutations.
The UV-light had an inhibitory effect in the whole range of the applied doses on the growth of colonies of algae from the cells inoculated on the solid medium immediately after irradiation.
Ethyl methansulphonate produced growth stimulation if applied in the lowest doses. The growth was inhibited in a further range of doses and then there appeared the range of lethal doses.
The growth responses to the influence of these mutagens were different in all the three algal species used and to the previous cultivation conditions before their exposure to the mutagens. It is certain that most of these growth responses are only modifications.
The influence of ethyl methansulphonate differed according to the method of application. If it affected the algae for a long time (it means if they were inoculated directly on the solid medium containing mutagens), or, if the algae were exposed to its influence immediately before their inoculation on the solid medium, the growth responses of colonies were quite different.
Growth responses with the single studied strains differed quantitatively only.

The main epicotyledonary axis inPisum sativum exhibits a very fluctuating either left- or right-handed deflexion of its first-order laterals, but the biserial buds on the laterals of various further order reveal in this respect certain regularities according to their position on the seedling, their deflexion being very often adaxial in the vicinity of cotyledons, however, in more distant and therefore later produced laterals, as a rule, abaxial. The integrant characteristics of these relationships may become clear from their experimental shift with the aid of exogenous auxin increasing inhibitions as well as of triiodobenzoic acid blocking the transport of endogenous auxin participant also in these embryonic-growth correlations.

Vascular inter-relationships between axillary bud, axillant leaf and axis have been studied in fives pecies of theSolanaceae, Lycopersion lycopersicum (L. )Karsten,Cestrum nocturnum L.,Cestrum diurnum L.,Withania somnifera (L.)Dunal, andDatura innoxia Mill. The phyllotaxy is alternate and the node is unilacunar with one or more leaf trace strands. The bud traces arise either from the trace of the subtending leaf or of the strands flanking the leaf gap. The vascular relationship between the bud, axillant leaf and main axis is discussed.

Irradiation with visible light reduced the mutagenic activity of 1-methyl-1-nitrosourea (MNH) and 1-methyl-3-nitro-1-nitrosoguanidine (MNG) solutions during their application onArabidopsis thaliana seeds for 24 hours. The antimutagenic effect of light was stronger with MNG than with MNH and in solutions buffered to pH 5 than in aqueous solutions. The decrease of activity of both the mutagens corresponded with the rate and degree of their photolysis. In the paper are presented the curves for the dependence of the decomposition of both substances and the formation of nitrous acid on pH and temperature of the solutions, amount of seeds.

In estimating the water-holding power and thus also their drought resistance, the portion of curvature as shown by the desiccation curves (transpiration, loss curves) appears most suitable in which the water-binding forces within a plant body feature a steep and characteristic rise. Since this portion of the curving stage coincides, in the majority of cases, also with the linear stage for the desiccation curves as described byCetl, this author's method of establishing drought resistance of plants (Cetl, 1953, 1957) may be applied to good advantage also to the woody species seedlings. For particularly urgent instances serving the purpose of orientation a modification of this method has been suggested, as follows: following cutting off the seedling the output of water is weighed at these intervals only: 0, 60, 120, and 240 minutes; as the criterion for drought sistance the resulting value for the rate of water output (v) is taken as measured between the interval of 60 and 120 minutes. When a detailed analysis is made it is advisable to consider the v value measured for the interval between 0 and 60 minutes and for that between 120 and 240 minutes. Moreover, it is likewise advisable to maintain the soil with experimental seedlings at the level of optimum moisture (60 to 80 per cent maximum capillary water capacity), for some 18 to 22 hours prior to the seedling's abscission.

The authors studied the growth intensity, the accumulation and distribution of nitrogen, phosphorus, and potassium in maize and pea plants under conditions of hydroponic culture. They found that RGR dropped by about 50% within 32 days of cultivation. The content (in mg/g dry weight) of nitrogen and potassium in maize, and of nitrogen and phosphorus in peas registered a substantial decrease, while the content of phosphorus in maize and that of potassium in peas exhibited a slight increase and a slight decrease towards the end of the experiments. The relative absorption rates of nitrogen and phosphorus in maize were maximum after 28 days of cultivation, while that of potassium reached a maximum immediately at the beginning; nitrogen and potassium absorption in peas reached maximum values after 28 to 30 days, whereas phosphorus was highest at the beginning. In the course of growth, the ratio of accumulated ions of N:P:K changed; maize accumulated relatively less potassium, and peas more nitrogen and potassium.

Electrophoreograms of protein extracts from leaves of the variety Lord Lambourne, detached at the flowering period toward the end of April, differed quantitatively from electrophoreograms of protein extracts from leaves detached from shoots at the end of May and June. Electrophoreograms of protein extracts of leaves from juvenile seedlings, detached at the end of May and June, did not differ from electrophoreograms of protein extracts of leaves from shoots of the variety Lord Lambourne detached at the same period. Electrophoretic pattern of protein fractions and the fractions of non-specific esterase from leaves differed from the corresponding electrophoretic pattern of flowers quantitatively and in some areas even qualitatively; the pattern of acid phosphatase differed quantitatively. The results obtained are discussed in relation to organogenesis.

Grains ofTriticum monococcum L. var.sofianum Körn. were treated with 0.1mm, 0.2mm and 0.3mm solutions of N-nitroso-N-methylurea (MNH), with 0.03m solution of buthylmethane sulphonate (BMS) and with X-rays in doses of 5 000r and 10 000r. The germination and development of individual colors of chlorophyl mutants were observed by the system developed byLamprecht (1960). All the mutants induced were classified according to their color changes into three main categories-homogenous unicolor, homogenous multicolor and heterogenous multicolor. In the last type the colors of individual leaves of the same plant varied. Anthocyanin mutations "albina" and "albino-transvirgata" sometimes coincided with the chlorophyll mutations. Some chlorophyll mutations showing complicated groups of colors appeared which were beyond the scale of classification by ordinary systems. The largest proportion in the spectrum of chlorophyll mutations, induced by MNH and X-rays was occupied by mutations of thealbina type. The broadest mutation spectrum in our experiments was induced by the application of 0.3mm MNH. The doses of X-rays used induced relatively higher numbers ofalbina-type chlorophyll mutations than MNH and BMS. In our experiments we succeeded in inducing on medium size samples ofTriticum monococcum L. var.sofianum Körn not only almost all types of chlorophyll mutations, induced byFujii (1960, 1962) andMatsumura (1960), but in addition also a great number of other even more complicated chlorophyll mutations, which have never been previously described inTriticum monococcum. L.

In young pumpkin plants, the phosphorus was found not to be affected substantially by potassium deficiency whereas the deficiency of calcium has marked effects. Potassium distribution is not affected substantially by either phosphorus or calcium deficiency.
In short-term experiments, the presence of calcium affects markedly the total uptake of potassium but the potassium distribution remains unaltered. The stimulation of potassium uptake is far more pronounced in plants pre-cultivated in a complete nutrient solution than in those pre-cultivated in a calcium-deficient one; this is apparently due to profound metabolic changes taking place in plants grown without calcium.
The reserves of phosphorus and potassium stored in the cotyledons are easily mobilized and translocated so that they can be used for growth in early stages of development; the appearance of pathological symptoms of phosphorus or potassium deficiency is thus prevented.

Chromatographic separation of an extract of organic acids on a Dowex-l column in the formiate cycle was used to study the content of several organic acids in pea plants, cultivated either in light or in darkness. Concentration changes of the individual acids in the course of growth indicate that the citrate cycle is blocked in the cotyledons of plants grown in light in the period around the 15th day of growth, probably at the site of succinic dehydrogenase (succinic and lactic acids accumulate and the content of citric and malic acids is exhausted). There is no inhibition in the cotyledons of etiolated plants. In vegetative organs, the concentration of the majority of the acids studied is lower than in cotyledons, probably because synthetic processes prevail over degradation processes in these organs. It seems that other processes besides the citrate cycle participate in malate synthesis in pea plants.

Internal symptoms in epidermal cells of tobacco rattle virus infected tobacco were investigated. Ring-, elipsoid- and spindle-shaped inclusions were found in the period between the fourth and thirtieth day after inoculation of Samsun seedlings.

Purification and preservation of potato virus X from leaf sap of tobacco plants before lyophilization was carried out by two methods: 1) precipitation by polyethylene glycol and ultracentifugation, and 2) precipitation by ammonium sulphate, chromatography on Sephadex G-50 and ultracentrifugation. The first method is preferable to the second because the final preparation contains more virus antigen. Both preparations were strongly infectious and maintained antigenic properties after lyophilization.
To achieve a more gentle course of lyophilization of virus preparations, addition of urotropine and dextran T-10 to the virus suspension, purified by the precipitation by polyethylene glycol-6000, was examined. Addition of urotropine was proved unsatisfactory, because only antigenic properties were maintained after lyophilization while the infectivity disappeared. But we can recommend addition of dextran T-10 up to a concentration of 6% to the preparation of virus antigen before lyophilization. The course of lyophilization is much rapider, the lyophilized product can be very easily dissolved in water and is not hygroscopic. The product is strongly infectious and gives the serological precipitation reaction in a dilution four times that of X virus antigen lyophilized without addition of dextran T-10.

Flower initiation induced by three inductive photoperiods inChenopodium rubrum L. was fully inhibited by treating the shoot apex with a 5 μl drop of 1×10^-5 m 5-fluorodeoxyuridine (FDU). This inhibition may be reversed by thymidine applied simultaneously with or after FDU treatment at any time during photoperiodic induction. One day after the end of induction the inhibition caused by FDU is irreparable even by increasing thymidine concentrations. It is concluded that photoperiodic floral induction may take place inChenopodium even if DNA synthesis is suppressed.

The mutual relationship between the water potential and water saturation deficit (w.s.d.) was studied on samples of leaf tissue of fodder cabage. Definite values of water potential were obtained by long-term exposure of plant material to an atmosphere with definite constant pressure of water vapour. The resulting w.s.d. values were determined gravimetrically.
Water saturation deficit varies indirectly with the water potential. This dependence was linear for values of water potential from -4.4 to -43.9 atm.
Since the stabilization of equilibrum of water potential between the leaf tissue and surrounding atmosphere was very slow the relationship between water potential and w.s.d. was influenced by the size of samples and by the length of exposure. Therefore this method was more suitable for relative than for absolute measurement.

In the years 1963-1965 the content of proline, asparagine, glutamic and γ-aminobutyric acids in young apple (Malus cultivars) shoots was studied. Two groups of apple varieties differing in frost resistance were included into experiments: the Yellow Transparent and Oberländer Himbeerapfel varieties as frost-resistant ones and-the Ontario and Reinette du Canada varieties as sensitive to frost. In the course of experiment γ-aminobutyric acid showed a relatively balanced level but glutamic acid, asparagine and especially proline were found in greater amount in the frost-resistant varieties. According to the results of this experiment the amount of proline-along with many other factors-can be considered as one of the indicators of the length of winter dormancy and also of the frost resistance of apple-trees at the beginning of the winter period.