The course of biosynthesis of fatty acids in the seeds of winter rape (Brassica napus L. ssp.oleifera, f.biennis cv. Třebíčská) was investigated. After the termination of flowering seed samples were taken at five intervals, the seeds were divided into 4 fractions according to size, and their weight, water content, oil content and fatty acid composition were determined. The oil content was found to increase in all size categories with time, with the exception of a minute drop when complete maturity is reached. Larger seeds contained more oil. The fatty acid composition changes with time in the individual size fractions almost continuously. The same holds for differences between seed sizes of the same sample. The main change in oil composition consists in the decrease of C₁₈ acids in favour of C₂₂ acids. Greatest decrements during maturation were found with oleic acid, less with linoleic acid. In absolute amounts the quantity of all synthesized acids rises, the greatest rise being observed with C₂₂ acids (i.e. predominantly erucic acid). It follows from the mean rates of synthesis of the individual groups (C₁₆, C₁₈, C₂₀, C₂₂) of fatty acids that the fraction of C₂₂ rate of synthesis increases, while that of the C₁₈ acids decreases with the same speed. The results indicate that the fatty acid synthesis is most intense during the second half of seed maturation, the main role being played by accelerating the synthesis of higher acids, especially of erucic acid.

The catabolism of specifically¹⁴C-labelled glucose during the root formation and its inhibition by kinetin and ethionine in the etiolated pea stem sections were studied. The formation of root meristematic foci in the pericycle region of sections was accompanied by the decrease of the C₆/C₁ ratio. Such a result and activation of pentose phosphate cycle, which was also checked by another method, suggested increased participation of pentose phosphate cycle in glucose oxidation. The above mentioned changes were also found after the prevention of root formation by ethionine and, therefore, do not seem to be specific for the meristematic foci formation. The growth of newly formed roots was closely connected with the rise of C₆/C₁ values.
The increase of CO₂ release from the first carbon atom of glucose molecule was recorded after the inhibition of root formation by ethionine.
The rise of C₆/C₁ values and decrease of pentose phosphate cycle activity was observed after the treatment of pea stem sections by kinetin in the first 64 hours after sectioning. In this case root formation was prevented and the growth of lateral buds was stimulated. The secondary xylem formation which took place later was accompanied by the activation of the pentose phosphate cycle. These phenomena are discussed in relation to cell division and biosynthesis of lignin-precursors.

We compared the occurrence of peroxidase isozymes in protein extract from roots, hypocotyls and cotyledons of 10 dayCucurbita pepo plants and of adult leaves of older plants by means of starch gel and polyacryl amide gel electrophoresis. We reached maximum discrimination by means of starch gel electrophoresis: 11 zones were ascertained on the cathode side and about 2 on the anode side at pH 3.1. Two zones occurred regularly:A and (the latter having a more complicated structure). ZoneD is characteristic for roots, but is it suppressed and seldom found with leaves. On the other hand zonesC ₁ andC ₂ are clearly discernible with leaves but are substantially less evident with roots. The character of anodic zoneZ is discussed later in this paper.

The cytoplasmic components of broad bean (Vicia faba L.) root tip cells were studied light- and electronmicroscopically. Using a light microscope, differences were revealed between cells from the cortex and from the central cylinder. For electron microscope studies the cells near the boundary between the mentioned parts of the root tip were selected at a distance of about 2 mm from the initials. The orientation of objects during embedding made possible fairly accurate localization. No peculiar, strikingly osmiophillic bodies were seen, which could be identified without doubt as osmiophillic platelets. It follows that some of the current cytoplasmic components, perhaps more or less altered were described as osmiophillic platelets. After fixation with KMnO₄, in which case the electronmicrographs are most instructive, the leucoplasts show several inclusions, mostly only partially limited against the matrix; it is not clear whether the true membrane is concerned here. The origin of intravacuolar membraneous formations is discussed.

The effect of different concentrations of hydrochloric acid on the qualitative an quantitative content of carbohydrates in humus fraction hydrolyzates was investigated. Three humic acid preparations were subjected to the usual procedure for obtaining fractions of humic and hymatomelanic acids. The carbohydrate content of the hydrolyzates was determined after their Chromatographic separation on Whatman 1, using the Partridge system and detection with acid anilin phtalate. The results showed that the qualitative carbohydrate content in the hydrolyzates of most humus fractions of samples used was identical. With increasing acid concentrations the amount of hydrolyzable carbohydrates usually increased, the total amount of carbohydrate in the hydrolyzate not exceeding 4% . The difference in the carbohydrate content as between hydrolysis with 0-9N and 5-3N HC1 was sometimes fourfold. A higher content of hexoses than of pentoses was generally found.

The liberation of phosphoric acid from glucose-1-phosphate, catalyzed by phosphorylase was studied in wheat growing in sand cultures with an addition of humic acid and hymatomelanic acid. It was found that the phosphorylase activity of tissues changes under the influence of humic acid very significantly. The maximum activity is reached at 10 mg humic acid/liter. The overground organs are less sensitive, as a stimulation effect is reached there only at 400 mg/liter. The effect of hymatomelanic acid is negligible in comparison with that of humic acid. The observed phenomenon is related to the effect of humus substances on the equilibrium of saccharides and on the distribution of dry matter in the plant.

In the basal growth medium only the ovaries excised 15 days after pollination reached maturity. In a medium containing IAA (5ppm) and kinetin (0.5ppm) ovaries excised even 10 days after polliration produced viable seeds.
Young ovaries formed in the pedicel region a callus, which later differentiated into roots; older ovaries (excised 15 days after pollination) produced callus tissue and roots from the ovary wall.

Distinct redox gradients were found in flowers and stalks of some plants. The ovary was found to be the most negative part in the whole pistil and more negative than the coloured perigon or corona leaves. These redox differences are in accordance with biopotential differences obtained in flowers by other authors.

Radish seedlings were grown in asymmetric magnetic fields. The number of seeds germinated and the dry weight of the plants were the two criteria by which possible effects were examined. Two experiments were done; in the first the plants were grown for an average of 7.7 days and in the second for 14.1 days. A statistical analysis of the results failed to reveal any significant difference between control plants grown in dummy magnets and those subjected to the magnetic influence.

Pea seeds were subjected to 1; 5 and 20 krad doses of⁶⁰Co γ-raýs. The irradiated seeds were planted in damp sand and in Petri vessels. After 10-daý vegetation at room temperature and under natural light conditions the content of the following components was determined in ýoung plants: free thiamine and thiamine pýrophosphate and drý substance.
It was found that 1 krad dose stimulates the growth of the plant and increases the crop of its green parts. The doses within the range of 1-5 krads do not affect the production of thiamine. The content of the latter, particularlý in its free form, increases markedlý for the dose of 20 krads. However, such doses hamper the vegetation.
In conclusion it seems that doses of the order of 1 krad lead to positive results in respect to the growth of the plants, however, neither thiamine biosýnthesis nor its phosphorýlation is stimulated under these conditions.

The author of this paper has attempted to clarify some problems concerning the nomenclature of Golgi apparatus and Golgi zone. The actual aim of this paper is to summarize - while using the more safe nomenclature-the existing knowledge about the functional relations between nucleus and cytoplasm arising from the study of the juxtanuclear zone by electron microscopy. Some observations lead to the assumption that the juxtanuclear zone is the place where cell components are formed or transformed. Considering its temporary character in proliferating cells and taking into account the connections with endoplasmic reticulum and the presence of pores, the nuclear membrane remains apparently a barrier restraining the spontaneous movement of substances and of cell components respectively between cytoplasm and karyoplasm that can be seen e.g. in the grouping of cytoplasmic formations in the juxtanuclear zone. In plant cells, within the zone mentioned agglomerations of different cell formations have been found, either the Golgi apparatus or mitochondria, secretion granules, lipid inclusions, vacuoles or plastids. Such a gathering of cytoplasmic material has been observed especially in young embryonic cells or in cells with retarded or stopped metabolism. The older and/or intensively active cells would then absolve an expansion of the cytoplasmic material into the whole cell. Similar formative mechanisms, now available for study during some ontogenic phases or at definite functional states only, could be effective even in the course of phylogenesis. From this point of view some of the formations described could be regarded as a kind of atavisms.

The effect of different constant soil moisture levels (90, 60, 30% and 90, 60, 40% respectively, of the maximum capillary capacity) on the vegetative growth of maize was studied by the methods of growth analysis. The constant soil moisture in vegetation pots was maintained by means of the injection method. The constantly decreased soil moisture was applied in one experiment just from the sowing of germinated corns and in the other from the phase of 4-6 leaves. In both the cases plants responded to the different soil moisture levels by a progressively lower growth rate of the total dry weight according to the degree of soil moisture lowering. When the constant soil moistures were applied from the sowing, the differences in the relative growth rate (R.G.R.) were caused mainly by lower leaf area ratio (L.A.R.) values. In the case of constantly lowered soil moistures from the phase of 4-6 leaves, the differences in R.G.R. were caused by lower net assimilation rate (N.A.R.). When the constant soil moisture of 40% was applied from the sowing, the changes in N.A.R. showed the characteristic features of adaptation to unfavourable conditions.

Obwohl auf Grund vieler Untersuchungen vermutet werden konnte, daß die sog. Kakteen-Eiweißspindeln, d. h. die ZelleinschlÜsse des Kakteen-X-Virus (CaXV), aus zahlreichen verlängerten Partikeln des OaXV zusammengesetzt sind, war das dennoch bis jetzt noch nicht bewiesen. Deshalb versuchten wir im Laufe dieser Untersuchungen mittels der fluoreszierenden Antikörper festzustellen, ob die Eiweißspindeln wirklich Aggregate von Viruspartikeln darstellen.
Bei dieser Untersuchung wurde die sog. indirekte Methode angewandt. Dabei haben wir zuerst die spindelhaltigen Zellen mit dem durch Immunisierung der Kaninchen hergestellten homologen Serum gegen CaXV behandelt, und erst nachher dieselben Zellen in eine Lösung von fluoreszierenden Antikörpern gegen das Kaninohen-γ-Globulin eingelegt. Nach dieser Behandlung leuchteten die Eiweißspindeln im Fluoreszenzmikroskop kräftig gelbrÜn (Fluoresce-inisiothiocyanat). Diese Fluoreszenz bewies uns, daß die positive Reaktion eingetreten ist und daß die Eiweißspindeln aus Viruspartikeln aufgebaut sind. Mehrere Kontrollversuche haben die Genauigkeit unserer Grundversuche bestätigt.

The activity of 1-methyl-1-nitrosourea (MNH), 1-ethyl-1-nitrosourea (ENH), 1-methyl-3-nitro-1-nitrosoguanidine (MNG) and 1-ethyl-3-nitro-1-nitrosoguanidine (ENG) was tested on seeds of barley andArabidopsis. The activity of nitrosoamides tested was expressed by the germination and M₁ seedling height reduction of barley and M₁ root length reduction ofArabidopsis.
1) After the action of both nitrosoureas (MNH and ENH) the germination of barley is at the same level as that of controls, even at concentrations, leading to a maximal reduction in the height of seedlings. After the action of both nitrosoguanidines (MNG and ENG) germination decreases in parallel with the decreasing seedling height. InArabidopsis no such differences in the relation germination to root length reduction were observed after nitrosoureas and nitrosoguanidines treatment. The differences in the M₁ generation of barley andArabidopsis after nitrosoguanidines treatment may be the reason for the non-mutagenic action of MNG and ENG in barley.
2) All 4 tested nitrosoamides are active between pH 3 and pH 6 and almost entirely ineffective at pH 7 and in basic solutions.
3) The effectiveness (in relation to M₁ seedling height reduction) of the tested nitrosoamides with a methyl group (MNG and MNH) is higher than of the nitrosoamides with an ethyl group (ENG and ENH).
4) 50% decomposition of aqueous solutions (at 25° C) of MNH and ENH takes about 60 hours, for MNG 120 hours and for ENG 420 hours.
5) Aeration during treatment or a period in the cold (5° C) after treatment improved the germination of MNG treated seeds. Sucrose, KNO₃ and thiourea had no effect.

Types of the daily course of transpiration rate were studied in two-year old seedlings ofPinus silvestris L.,Picea excelsa L.,Larix decidua L.,Tilia cordata Mill., andAlnus glu-tinosa (L.) Gaertn. The curves illustrating the daily development of transpiration rate (Figs. 3 - 8) may be grouped in two types, showing a midday maximum (one-peak curves) and a midday depression (two-peak curves). Unlike herbaceous plants, the seedlings ofPinus silvestris L. were found to show, during the night-time, lower but not negligible values for the rate of transpiration (see Figs. 3 and 8). The following times are considered most suitable in determining the rate of transpiration for both herbs and woody species during the daylight: 09.0, 12.0, 14.0, and 17.0 hours. For the forest species seedlings further times are suitable for the night-time, as follows: 23.0, 01.0, and 06.0 hours. The rate of transpiration in the seedlings of Pinus silvestris attained very low levels at 3 and between 6 and 8 a.m. and between 6 and 8 p.m. (see Figs 3 and 8).

The enzymatic transamination reactions between aspartic and α-ketoglutaric acid and between aspartic and pyruvic acid were studied in fresh dialysed extracts of young wheat plants cultivated under various trophical conditions, in mineral solution (Knop), in the solution of an soil organic substance (potassium humate) and without nutrients (H₂O). Simultaneously, the level of endogenic aspartic acid, glutamic acid and the growth values were determined. The enzymatic reactions were characterized by determining the optimum pH, the time course, and the effect of coenzyme and of inhibitors.
The activity of the aspartate-glutamate transaminase from the root system of plants was considerably higher than the activity of the overground organs. The enzymatic activity from both parts of the plant was inversely proportional to the growth rate: intensive growth of the plants from the Knop variant was connected with their low enzymatic activity; the level of endogenic glutamic acid was high. The slow growth of the plants without nutrients was connected with a higher enzymatic activity; the level of endogenic glutamic acid was low. The plants from the potassium humate variant had an intermediate position between these two variants from the point of view of growth as well as from that of enzymatic activity. The plants with insufficient nutrition (slow growth, low level of endogenic glutamic acid) apparently have a low capacity for supplementing the glutamic acid deficit, which is essential for the metabolic processes, by increasing the activity of the reactions leading to glutamic acid synthesis (Asp-Glu) and, on the other hand, by decreasing the reactions utilizing it (Glu-Ala). For wheat plants the active aspartate-glutamate reaction is obviously physiologically more important than the direct reaction glutamate-aspartate and the reaction aspartate-alanine which in all cases had a very low activity.

The cytological analysis of 25 Yugoslav rye populations, collected from Slovenia Serbia and Macedonia, showed the presence of B chromosomes in the all populations analysed (100%). The number of B chromosomes present was small, from 1 to 3, while the average number per plant ranged from 0-13 to 0.97. The frequency of rye plants with B chromosomes for Yugoslavia had an average of 27.10%. The frequency of plants with B chromosomes and the average number of that chromosome category per plant were appreciably greater in the arid region of Macedonia than in the humid region of Slovenia, the differences being significant and real biometrically.
Comparing the data of other authors for primitive Asian rye populations, it was established that the B chromosome frequency is lowest in the populations from regions designed as centres of the origin of this plant species (Near East, Asia Minor), with a considerable successive increase of their frequency further as well toward the East (Transbaikal, Korea), as toward the West (Balkan Peninsula, Yugoslavia). Possible causes of the B chromosome frequency increase in the populations out of the centres of rye origin were discussed, and it was pointed out to the importance of their study in primitive West European populations.

The paper deals with the effect of the application of certain ions (Zn²⁺, B₄O₇ ^2- Mn²⁺, Cu²⁺, MoO₄ ^2-,) on the development of the activity displayed by amylase, urease, and glutamate-oxalacetate (GOT) in hydroponically cultivated barley during the first seven days of ontogenesis. The enzymes were studied separately in the overground and root parts of the plants. The following main conclusions can be drawn from the findings made: The amylase activity of the control plants in connection with their development diminished slightly in the overground part, while it was relatively constant in the roots. Due to the effect of certain elements tested, this activity increased pronouncedly (significant differences were confirmed in variants containing MoO₄ ^2-, Zn²⁺, and Co²⁺). The urease level in the overground part of the control plants remained low throughout the entire experimental period and was only little influenced by the individual microelements under study (with the exception of B⁴O₇ ^2-). On the other hand, the urease activity in the root system increased markedly, the B₄O₇ ^2- ions exhibiting a significantly stimulating effect. The activity of glutamate-oxalacetate transaminase (GOT) in the overground part of the control plants increased only slightly in the course of the initial development, while in the root system it grew relatively more pronouncedly. In the overground part of the plants all the microelements administered displayed a significantly depressive effect on the development of this enzyme activity; in the roots, the inhibitory action was maintained only in the last experimental period in variants with Zn²⁺ ions.

The applicability of the microrelief (or reprint) method for stomatal aperture determinations was studied in middle-aged sugar beet leaves. It was found that the picture of the central aperture (CA) of stomata on the reprints could be observed only if their eisoiial aperture (EA) was sufficiently wide. If the width of EA was small (about 1-3 μ), it was impossible to determine the width of CA by means of the reprint method, in view of the proportional dimensions of the upper closing flaps. A lower concentration of the chlorophorm solution of methylmethacrylate used for taking reprints had a favourable influence on the amount of stomata whose width of central aperture was reproduced on the reprints. Simultaneous measurements of the EA-width and of the diffusibility of leaves (determined porometrically) in the course of a day showed, on the whole, fairly corresponding changes. During the wilting of detached leaves their diffusibility fell to zero, where it remained. The width of EA also decreased at first, but at higher water deficits it partly again increased.

A method of calculation for determining the total transpiration (consumption of water for transpiration) of a single woody plant seedling or of their growth during periods of different length (from one day up to the whole vegetative season) is described and critically evaluated; the calculation is performed according to single transpiration intensity measuring results, by the cut-shoot method and weighing at 8, 11, 14 and 17 hours (or more often during the day).

The cotyledonary petioles inPisum sativum developing at the start of germination, as well as the cotylaries growing out after decapitation of thePisuin seedlings manifest very often the so-called lateral correlations, since one of them suppresses the opposite primordium when the growth inhibition in the plant coinciding apparently with the growth promotion results necessarily in a normal development only of one of these originally equal primordia. These correlations also seem to be mediated by auxin, being induced by gravity or by corresponding cotyledon and root products, which can be supported by the use of exogenous auxins.

It has been established that mannitol infiltrated in a vacuum into plant tissues increased the oxygen uptake. No lag phase appearing subsequently to its infiltration by the transpiration stream (Trip, Nelson, Keotkov 1963) was observed. Our results may support the opinion that the mentioned lag phase is caused by the slow penetration of mannitol into the plant cells.

U odr. Blenheimská reneta se postřiky α-naftyloctové kyseliny na letorosty strormů bez plodů neprojevily vyšším počtem založených květních pupenů. Autor proto dospěl k názoru, že otázka přímého zapojení a přímého vlivu α-naftyloctové kyseliny na zakládání kvétních pupenů u jabloné je sporná.

When the lethal radiomutant chlorina 42 was cultivated on glucose containing and glucose-free medium the cotyledons of the matant sown on glucose medium had a higher chlorophyll content than those of the matant sown on glucose-free madium. In further cultivation of this mitant on glucose medium until flowering the total chlorophyll content is maintained at the same level, it increases slightly in the case of flowering plants. The mutant cultivated on glucose medium differs somewhat with regard to the content of free amino acids from the green control cultivated also on glucose medium over the whole vegetation period. The former has a higher glutamine content than the latter and in some growth phases also a higher content of asparagine. It is assumed that the insufficient photosynthetic activity is apparently not fully compensated by glucose and the plant has to supplement its energy balance by partial oxidative protein catabolism even under the conditions of artificial nutrition.

When compared with the control plants, the increase in dry weight in the growing parts of germinating plants ofPisum sativum L., cultivated in a closed atmosphere in darkness or light is heavily inhibited. The concentration of carbon dioxide in the closed atmosphere increased in 60 mg CO₂/per 1 g of the final dry weight of plants after 10 days. Similar results were obtained with older plants under similar conditions. The Knop solution caused a slight increase of dry weight in the growing parts of plants, but did not change considerably the relations in gas exchange. The results show that even plants which are able to photosynthetize, are only transpiring under the above conditions; first, when the plants were devoid of cotyledons, as storage organs, the changes in their dry weight (but not the changes in the CO₂ and O₂ exchange in a closed atmosphere) seemed to show photosynthetic income of CO₂ (while its concentration increased to 3-6 volume %) when compared with the control.
From the above results follows that quantative relations between photosynthesis respiration cannot be solved by analysing the gas exchange in a closed atmosphere.

A study of the effect of exogenous sugars (fructose, glucose, arabinose and xylose) on Qo₂ inChioreila pyrenoidosa (A 82) and inScenedesmus obliquus (A 125) showed that the effect of sugars on respiration depends on previous cultivation of the alga. In autotrophically cultivated algae all sugars contribute to the increase of Qo₂, in those cultivated rnixotrophically (with the addition of glucose or together with yeast extract, and with xylose) this occurs only in Scenedesmus when glucose or xylose are applied. The effect of cultivation was apparent in that mixotrophically cultivated algae had larger endogenous reserves of substrates than the autotrophic ones. The exogenous substrate is not preferentially respired and does not affect respiration solely as its substrate. In Chlorella, the effect of different cultivation conditions is more pronounced, the QO₂ being usually higher than inScenedesmes.

In der Arbeit wurde die Möglichkeit der allelopathischen Beeinflussung von Folgepflanzen durch Vorkulturen bei der Kultivierung in abgestuften Zeitintervallen nacheinander auf demselben Bodensubstrat bei folgenden Konabinationen von Pflanzen untersucht: Mohn - ZuckerrÜbe, Ackersenf - Gerste, Hanf - Korn, Zwiebel - Raps. Die Versuche wurden in Gefassen mit Komposterde, welche im Laufe des Versuches im Garten in den Boden eingelassen worden waren, durchgefÜhrt. Es wurde das Wachstum der Vorkulturen und der Folgepflanzen in den ersten Wachstumsphasen untersucht. Von der Aussaat der Folgepflanzen wurde in Bodenproben die Respirationsintensität, die aktuelle Feuchtigkeit und der Gehalt an physiologisch zugänglichem Stickstoff, Phosphor und Kalium bestimmt.
In allen untersuchten Kombinationen waren die Folgepflanzen durch die Kultivierung der Vorkultur und die nachfolgende Lagerung des Bodensubstrates beeinflusst. Die Wachstumsveränderungen der Folgepflanzen standen teilweise mit dem Gehalt an physiologisch zugänglichem Stickstoff im Bodensubstrat in Korrelation. Aus dem Charakter der Wachstumsveränderungen ging jedoch auch klar hervor, dass sich hier auch allelopathische Faktoren beteiligt haben. Sehr inhibierend wirkte Mohn auf ZuckerrÜbe, weniger inhibierend wirkte Ackersenf auf Gerste und Zwiebel auf Raps. Die Wirkung von Hanf auf Korn zeigte mit der Lagerungsdauer des Bodensubstrates zusammenhängende Veränderungen.
Veränderungen im Gehalt an physiologisch zugänglichem Stickstoff, Phosphor und Kalium im Versuchsbodensubstrat entsprachen nicht der Menge der angewachsenen Pflanzenmasse der Vorkultur, was durch die angewendete Kultivierungsmethode bedingt war. Die verhältnismässig schnelle Erneuerung der durch die Vorkultur erschöpften Nitrate im Versuchsbodensubstrat in der Zeit der Bodenlagerung wurde wahrscheinlich durch Nitrifikationsprozesse verursacht.
Den festgestellten Veränderungen der Respirationsintensität des Versuchsbodensubstrates nach kann sich auch die Bodenmikroflora an der allelopathischen Beinflussung beteiligen.

The paper deals with the study of morphological differentiation of flower buds in 10 varieties of apple-trees in relation to the growth of summer shoots and the earliness of varieties. The data obtained indicate that in the warmer regions of Slovakia the critical season of transformation of flower buds from vegetative to generative forms takes place, on the average, between July 20 and 29, and, at the same time, the variety Yellow Transparent deviates from the average four week-earlier. According to the author we can speak neither of a positive relation between the onset of morphological differentiation and the active growth of summer shoots nor of the relation between the earliness of the variety in maturing and the onset of differentiation. The morphological differentiation may be classified into five phases: 1^st phase - the formation of the growing point primordium, 2^nd phase - the formation of the cup on sepal primordia, 3^rd phase - the formation of petal primordium, 4^th phase - the formation of carpel and stamen primordia, 6^th phase - completion of the differentiation through substantial enlargement of flower organs before the onset of winter.