White-rot fungi causing the white decay of wood, secrete polyphenol oxidase type enzymes which catalyze the oxidation of diphenols to quinones. If the substrate also contains amino acids, they can be oxidized secondarily to a red pigment, the intensity of which depends on the activity of oxidation oxoenzymes. This finding was used for devising a quick test to demonstrate the oxidases secreted into the cultivation medium by wood-rotting fungi. As substrates we used hydroquinone and glycine. We tested a total of 89 species and 131 strains of wood-rotting fungi. Simultaneously, we compared the newly devised test with the most common test for the detection of polyphenoloxidases, with the guaiacol test. It follows from the results that the new test, in which the intensity of the red colour was estimated colorimetrically, permits to divide the wood-rotting fungi into two groups, the positively and the negatively reacting ones. This division does not fully coincide with that obtained by means of the guaiacol test.

Coleoptile and root tips ofTriticum aestivum cv. Arnej 624 and those ofAvena sativa cv. Victory (Svalöf) as well as dry excised embryos ofTriticum aestivum cv. Rival (Svalöf) and those ofArachis hypogaea cv. 34 3A. H. were cultivated in media containing various concentrations of sucrose and growth regulators, like ascorbic acid, indole-3-acetic acid and gibberellin. Growth, differentiation and water uptake of the various explants were determined at regular time intervals. Further, the concentration of the endogenous ascorbic acid in mg./g. fresh weight, as well as the amount of this growth regulator utilized as per cent of the total were determined.
Although all the three growth regulators promote growth in the explants, their effect is best felt when sucrose of a higher concentration (1.0 per cent) is added to the medium. In fact, the response to 1.0 per cent sucrose is sometimes as good as a combination of a growth regulator with sucrose, especially in the case of root explants.
The results clearly indicate that the biosynthesis of ascorbic acid in the explants is catalyzed by the addition of indole-3-acetic acid as well as gibberellin. Simultaneously, the utilization of ascorbic acid is also appreciably increased by the presence of these growth regulators.
Addition of 1.0 per cent sucrose to the medium containing the above mentioned growth regulators augments to a considerable extent not only the concentration of ascorbic acid, but also steps up its utilization. Enhancement of ascorbic acid as well as its increased utilization are correlated with rapid imbibition of water, growth and differentiation.
The role of ascorbic acid in growth is discussed; and on the basis of the data presented here it is postulated that: (1) auxin and gibberellin function in the growth process by catalyzing the biosynthesis of ascorbic acid; and (2) that ascorbic acid not only participates in activation of various enzyme systems, but also stimulates the production of adenosine triphosphate by acting as an electron donor in photosynthetic phosphorylation as well as oxidative phosphorylation; (3) that the above action of ascorbic acid creates a favourable redox balance for synthesis of nucleic acids, proteins, enzymeproteins, and cell-wall constituents, thus enabling the processes of cell division and enlargement to proceed at a fast rate; and (4) that the relative rates of cell division and cell enlargement as well as "ageing" will determine the pattern of plant development.

Schizaphis graminum (Rondani) is proved to be an additional vector of maize mosaic virus (MMV). The pH range for the infectivity of the virus in extracted juice is found to be from 4.4 to 9.0, the optimum being 5.6 to 7.2. Effect of certain chemicals on the virusin vitro has also been studied. Cross protection between MMV and Sugar-cane mosaic virus (SMV) indicated positive results. It has been concluded on the basis of similar physical properties, tolerance towards certain chemicals, host range, symptomatology, aphid vectors and positive immunological tests, that MMV and SMV are related viruses.

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.

Die Wirkung steigender Konzentrationen von NaHCO₃ auf die Ausfällung des Eisens in einer Nährlösung sowie die durch das Hydrogenkarbonat bedingte Hemmung des Wachstums der Pflanzen (begleitet von Chlorose) und zugleich die Gegenwirkung des Na-Humats wurden erforscht. Unter der Einwirkung von NaHCO₃ wurde eine Verminderung des Eisengehaltes und eine Erhöhung des Verhältnisses P/Fe in den Sprossen festgestellt; in Anwesenheit von Humat in der Nährlösung blieb dieser Effekt aus.

6-azauracil (AU) and 2-thiouracil (TU) were applied to the short-day plants Pharbitis Nil and Chenopodium rubrum and to the long-day plants Hyoscyamus niger, Lolium temulentum and Triticum aestivum cv. Chlumecká 12 at different times before, during or at the end of floral induction. In wheat the effect of 5-bromouracil, 5-iodouracil and 2-thio-6-azauracil was also tested.With the exception of bromouracil, which slightly stimulated flowering in wheat, all analogues either strongly inhibited or completely blocked flowering when applied in appropriate concentrations a short time prior to induction or at its beginning. Treatments given a longer time before induction or after its termination was less effective. Inhibition of flowering was always associated with damage to the vegetative growth. The effect of TU was reversed by uracil and that of AU by uridine, if these compounds were applied simultaneously with the analogue at a concentration exceeding at least 5 times that of the analogue. Reversal also applied to vegetative growth. Simultaneous application of gibberellin and analogues did not remove the inhibition.

Metabolic disturbances inNicotiana glauca, a symptomless carrier of potato witches' broom were studied. The dry weight content of leaves of diseased plants was slightly decreased, that of the stems increased. The ash content in the dry weight of the whole diseased plant was decreased by 11%. Contrary to tomato plants which had shown considerable disproportions in the distribution of metabolites among the individual organs investigated (ULRYCHOVÁ, LIMBERK 1964), the content of the total nitrogen and of the individual nitrogen fractions of both leaves and stems of diseasedNicotiana glauca were decreased. The content of glutamine was increased in both organs in spite of the decrease of ammonia nitrogen by nearly 30% in both cases. The most striking disturbance found in the diseased plants ofNicotiana glauca was the 67% increase of a low-molecular phosphorus fraction (P extractable with 0-2N HCIO₄) in the leaves. This result agrees with that found in diseased tomato plants and may be primarily associated with the virus infection. The content of all other phosphorus fractions of both leaves and stems was decreased.

The purpose of this paper is to determine the sequence of the formation of the lignified cell wall and to confirm the hypothesis expressed previously on the alternate deposition of cellulose and lignin in a 24-hour period. In this connection, the inner surface of the cell wall of the fibre cells from the youngest wood ofPopulus nigra L. 'Italica' taken during a typical summer day in two-hours' intervals was investigated electron microscopically.
The fine structure of the inner surface of the growing secondary cell walls was found to change regularly within 24 hours and to be determined by the structure of the components just being deposited. Cellulose and lignin were identified unambiguously, hemicelluloses could not be identified by their structure. The cellulose was characterised by the parallel microfibrillar structure; lignin was detected as an amorphous deposition.
The identified structural components are being deposited separately in certain intervals of the day cycle: cellulose in the afternoon hours (12 a. m. - 6 p. m.) and lignin after midnight (0 - 4 a.m.); in the morning hours (6-10 a.m.), neither lignin nor cellulose are deposited, however, the structure of the cellulose formed previously rises as a microrelief under the amorphous layer.
The alternate deposition of both structural components corresponds to variations of the biophysical and biochemical condition of the cells observed in the cambial zone during 24 hours. This periodicity appears to be autonomous and affected only partly by environmental factors. The results confirm the presumption that each lamella of the secondary wall consists of a cellulosic and a non-cellulose (lignin) part. Lignin permeates through the cellulosic part formed previously, impregnates it and cements it to the preceding lamella.

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.

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.

Azo-coupling methods were used for demonstrating non-specific esterase in the wheat root in all parts of a transverse section, usually with the exception of the woody parts of the vascular bundle. The central cylinder gave a more intense reaction than the primary cortex and the rhizoderm. The reaction was not inhibited by dodecyl sulphate. A weakening of the reaction intensity was observed after application of AgNO₃. The Tween method did not yield reliable results.

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 vessel member length-diameter and perforation plate-vessel member length relations inDioscorea alata L. have been investigated. The two types of vessel elements, one with scalariform perforation plate and the other with foraminate perforation plate, have been considered for correlation tests; the variables being vessel member length and diameter, and vessel member length and perforation plate length. Significant positive correlation was found only in the case of perforation plate length and vessel member length for types with scalariform perforation plates.

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.

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.

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 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.

An investigation was made as to whether the cultivation conditions of algae affect their respiratory metabolism. Chlorella pyrenoidosa (82), Scenedesmus obliquus (125) and Euglena gracilis (259) were cultivated both in a static and shaken culture.
It was found that shaking considerably affects the respiratory metabolism of algae. The shaken cultures, in contrast to the static ones, display a higher O₂ consumption and have mostly a different RQ. It is possible that the differences observed are due to accelerated development and ageing of the shaken cultures.
It thus appears that shaking is an important factor in cultivation which must be taken into account during growth of experimental material. The values of RQ found here to be about 1-3 point to the fact that anaerobic glycolytic processes can proceed even under fully aerobic conditions. The culture of Scenedesmus obliquus (125) appears to have a less adaptable metabolism and does not respond to environmental changes as readily as Euglena gracilis or Chlorella pyrenoidosa.

The described virus of cow-parsnip,Heracleum sphondylium L., was found in three ruderal localities of Greater Praha. The symptoms are manifested by decolorations which consist of bright yellow areas spreading from the centre of the leaf blade along the main veins. These symptoms appear severely in May. Under higher temperatures and in a chronic stage of infection the symptoms are more or less masked. The disease is mechanically transmissible to parsley, coriander, parsnip, dill, sowbane,Chenopodium quinoa and C.giganteum. The author failed to transmit the disease to celery, carrot, caraway and to 27 species of differential host plants, he failed in the transmission of the virus by the dodder,Cuscuta campestris YUNCK., too. Thermal inactivation point of the virus lies between 51° and 55° C. Infectivity of extracted sap was lost after 2 days at room temperature.

If both cotyledons are amputated from non-decapitated pea seedlings, the intensity of transport of³²P into intact epicotyls is raised more than twofold. This is apparently connected with the regulatory-inhibitory effect of the cotyledons that can be simulated by a 0.1% paste of indoleacetic acid (IAA). If both amputated cotyledons are replaced by this paste, the intensity of³²P transport is again decreased to the level found in plants with intact cotyledons.
When etiolated pea seedlings grown in the dark in 100% relative humidity were decapitated, the³²P transport to the top of the epicotyl stumps covered with 0.5% IAA paste was strikingly decreased if the stumps were covered below with a 10% paste containing chlorocholine chloride (CCC) or with a 0.5% paste containing triiodobenzoic acid (TIBA). On the other hand, the intensity of³²P transport was significantly increased if the IAA paste was put above a 0.5% paste with kinetin which alone does not raise the transport intensity. No such synergism toward³²P transport could be established between IAA and gibberellin.

The changes of stomatal and cuticular transpiration of bean plants were investigated by graphical transpiration curves method (Slavík 1958). Bean leaves were infected by fungusUromyces appendiculatus (Pers.) Link. After the infection the intensity of stomatal transpiration had a decreasing tendency. Beginning with the sixth day after infection, the proportion of stomatal and cuticular transpirations becomes more expressive, i.e. the leaves transpire more by cuticles than by stomata. The higher share of cuticular transpiration brings extensive water relations to the diseased plants.

In der Arbeit wurde der Einfluss der Vorkulturen von Lein, Korn, Mohn und Ackersenf auf die folgenden Kulturen der gleichen oder einer anderen Art bei unmittelbar aufeinanderfolgenden Aussaaten sowie bei Aussaaten nach verschieden langen Intervallen unter Abstufung der Dauer der Lagerung des Bodensubstrates untersucht. Die Versuche wurden in Gefässen mit Komposterde durchgeführt, die im Versuchsgarten aufgestellt worden waren. Es wurde das Wachstum der Erst- und der Folgekultur mit Hilfe der Bestimmung der Trockensubstanz der oberirdischen Teile und der Wurzeln gewertet. Im Laufe der Wachstumsentwicklung der Folgepflanzen wurden Bodenproben entnommen und in denselben der Gehalt an physiologisch zugänglichen Stickstoff-, Phosphor- und Kali-Mengen bestimmt.
Alle vier in Betracht gezogenen Vorpflanzen bewirkten nachweisbare Veränderungen des Wachstums der Folgepflanzen. Lein und Mohn wirkten auf lein und Zuckerrübe als Folgepflanzen durch autopathische oder allelopathische Faktoren im Boden. Die Wirksamkeit von Korn als Vorpflanze auf Korn und Ackersenf als Vorpflanzen auf Gerste war nicht so deutlich. Von den Ergebnissen der beiden letzten Fälle lässt sich nicht direkt auf das Vorhandensein autopathischer oder allelopathischer Faktoren schliessen.
Bei unmittelbarer Kultivierung von Folgepflanzen im Boden der Vorpflanzen ohne Lagerung wurden nur Wachstumshemmungen festgestellt. Versuche mit abgestufter Lagerungsdauer bieten die Möglichkeit eine ganze Skala von Wachstumsänderungen an den Folgepflanzen von der Hemmung bis zur Stimulierung zu erfassen. Die Wirksamkeit der Vorpflanze auf die Folgepflanze ändert sich erheblich mit der Lagerungsdauer des Bodens nach der Vorpflanze.
Die Wachstumsänderungen der Folgepflanzen ergaben mit Ausnahme der Versuche mit Korn und teilweise mit Ackersenf weder Beziehungen zu den Veränderungen des Gehalts der untersuchten Nährstoffe, noch auch zur angewachsenen Pflanzenmenge der Vorkultur.

In den Ksimwurzeln eines Kultivars vonPhaseolus vulgaris nanus sind in der Wurzelspitze die Zellen in Päckchen von meist vier oder acht Zellen, die von einer gemeinsamen Zelle abstammen, angeordnet und gut voneinander zu unterscheiden. Diese Anordnung bestätigt den Befund von WAGNER (1937), dass jede Zelle des Wurzelmeristems vom Augenblick ihrer Entstehung an nur eine geringe Anzahl von Teilungen durcl.macht, da die Zellgruppen höchstens aus aeht oder neun, meistens aber aus vier Zellen bestehen. Ausserdem sind diese Zellgruppen in ziemlich gut unterscheidbaren Querscheiben angeoidnet, so dass es scheint, dass die Erstlingszellen jeder Querscheibe rbytmisch, allerdings nicht absolut gleichzeitig, gebildet werden. Obzwar es scheint, dass die Mitosen in der Wurzelspitze unregelmässig verteilt sind, ist es doch nicht der Fall. Das Wachstum der Zellen sowie ihre Teilung gehen rhytmisch vor sich.

Die modellmässige Erfassung der Wachstumsverhältnisse bei höheren Pflanzen setzt die Möglichkeit einer Markierung des gesamten, von einer bestimmten Zelle sich herleitenden Gewebes voraus. Derartige Markierungen sind etwa bei der Entmischung eines heterogenen Chloroplastenbestandes einer Zelle, bei Polyploidisierung einzelner Zellen und der sich aus diesen herleitenden Geweben sowie bei künstlichen z. B. mittels Röntgenstrahlen induzierten Mutationen gegeben. Mutiert im letzten Falle etwa eine Initiale der L II, so weist ein gewisser Anteil der sporogenen Masse die gleiche Mutation auf. Unter der Voraussetzung fehlender Zellelimination entspricht dieser Anteil im Durchschnitt dem Verhältnis unserer mutierten zur Zahl der übrigen an der Weiterentwicklung beteiligten Initialen der L II. Das bei dieser Gegebenheit sowie unter den in der Abhandlung im einzelnen aufgeführten Voraussetzungen aufgestellte Modell gibt vor allem Auskunft über die in der Selbstungsnachkommenschaft mutierter Pflanzen zu erwartende Häufigkeitsverteilung der Mutationen und Spaltungsverhältnisse.
Der Vergleich mit beobachteten Daten zeigt, dass für die Beschreibung der bei Gersten-sprossen vorliegenden Verhältnisse ein relativ einfaches Modell ausreicht. Ihm liegt die Annahme zugrunde, dass die Initialen voneinander stochastisch unabhängig mit einer gewissen, dem Zufallsgesetz folgenden Wahrscheinlichkeit überleben und gleichfalls in Abhängigkeit vom Zufall mutieren. Dabei braucht innerhalb der untersuchten Seitensprosse eine Elimination der ursprünglichen Initialen nicht angenommen zu werden.
Bei der Erbse liegen die Verhältnisse sowohl hinsichtlich der Häufigkeitsverteilung der Mutationen wie der Spaltungsverhältnisse erheblich komplizierter. Bisher sind bei dieser Art nicht die Verhältnisse bei Einzelinfloreszenzen, sondern im allgemeinen bei ganzen Pflanzen bekannt. Ihre Deutung setzt die Annahme voraus, dass im Verlauf des Wachstums an bestimmten Stellen eine Elimination einzelner für die Bildung der sporogenen Masse verantwortlicher Zellen erfolgt. Die Untersuchungen an diesem Modell sind jedoch noch nicht abgeschlossen.

Treatment of seedlings ofPimpinella monoecia with colchicine-gammexane lead to the production of tetraploids. The tetraploids besides showing the meiotic anomalies like univalents, split spindles, multiple spindles, micro-nuclei, nondisjunction, strays, etc., exhibited pollen grains which were triradiate, triangular and quadriradiate while the controls had only one type of bipolar radiosymmetric grains. They have been classified into different types and their frequency has been determinod. A scheme has been presented representing the development of these variable grains from the control type A, which is based on the observation of grains showing intermediate stages. Explanation of this pollen variability has been presented.

The possibility of passage of the oat sterile-dwarf virus by the leafhopper Calligypona pellucida F. as vector was studied in the years 1961-1964. Females infected in a greenhouse as well as in nature produced 6,000 eggs from which some 3,500 nymphs hatched. Of these, 3,423 were subjected to individual testing on oat seedlings. In seven cases (0,2%) a transfer of the studied virus through eggs of infected females to their offspring was observed. The infectivity began to manifest itself 9-23 days after hatching.