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.

It was found by measuring the length of the cortex cells of the root tips of the broad beanVicia faba L. that the beginning of the elongation zone lies at about 1-2 mm from the initials and its end at about 7-8 mm from the initials. Shrinkage of the object during microtechnical treatment was negligible. The autonomy of the individual tissues of the root tip was taken into account.

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.

Cinematographic records of longitudinal growth showed that hypocotyl with radicle inPisum sativum L. undergoes spiral oscillations during growth. This phenomenon can be characterized by the following time-space limits:
(1) Curvature of the hypocotyl with radicle takes place always in the zone of most rapid elongation (Fig. 2, 8).
(2) Maximum deflections of the root tip from a straight positive geotropic direction of growth correspond to the time when the maximum growth rates were demonstrated (Table 4, Fig. 8).
(3) Shift of zones of maximum elongation proceeds in a spiral path, acropetally to the region of the root tip; as may be seen from the results obtained by studying the growth of roots of perennial (woody) plants this mechanism is preserved throughout ontogeny (Head 1965).
When studying these self-regulating mechanisms the author suggests to use the principles valid for control systems with feedback as a mechanism eliminating errors.

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.

Experiments with youngHordeum sativum andHelianthus annus plants showed that in the excretion of mannitol in the guttation liquid observed byGroenewegen andMills (1960) after uptake by the root system of plants, the osmotic concentration of mannitol in the nutrient medium and the temperature are significant. The beginning of mannitol excretion during guttation is accelerated considerably by the increase of the osmotic concentration of mannitol in the nutrient medium and the rising temperature. The osmotic concentration of mannitol is also important for the duration of mannitol excretion in the guttation liquid after transfer of the plants into a nutrient medium without mannitol. In the presence of mannitol in the nutrient medium water uptake by the root system and growth are inhibited and the tissues of the organs above ground and of the root system are dehydrated. The inhibitory effect of mannitol on the water uptake by the root system is immediate.

Measurements of the size of the nuclei of dioecious plants showed that the nuclei of male and female plants differ in agreement with the larger quantity of chromatin. The male. plants ofRumex acetosella andMelandrium album had larger nuclei, their Y chromosome being larger than the X chromosome, the same is true forRumex acetosa where the Y chromosome is smaller but there are two in the set.Ginkgo biloba had larger female nuclei because the Y chromosome was smaller than the X. The curves obtained by grouping all the nuclei of both sexes never had two peaks with regard to the small differences between the classes of maximum frequency.

In dieser Arbeit wurde die Wirkung von 55 Verbindungen der Pyridinreihe in der Konzentration 10^-3 m geprüft. Bei diesen Untersuchungen wurde die Grundgruppierung. die der Träger der Phytotoxizität ist, gefunden. Es wird die abhängigkeit dieser Wirkung von der Konstitution der Substanzen solehen Typus diskutiert. Verbindungen vom Typus VII verursachen eine Wachstumshemmung der Hypokotylen und besonders eine sehr starke Hemmwirkung des Wurzelwachstums, die meistens mit Chlorose verbunden ist. Zu den wirksamsten gehört 3-Styrylpyridin und manche seiner Salze. Eine starke Hemmwirkung auf das Wachstum ohne Chlorose verursachten diese Verbindungen auch beiCucumis sativus.

The content of endogenous gibberellins was determined chromatographically in the roots 14-17 days old pea seedlings cultivated in water cultures in the dark. When the epicotyls are amputated from these plants, the content of endogenous gibberellins increases significantly within 6-12 hours after amputation as compared with the intact controls, then it falls off again considerably up to 24 hours after amputation. The initial increase of the gibberellin level in the roots can be explained by transport inhibition of the endogenous gibberellins from the root to the epicotyl, the later decrease of this level to be interpreted as inhibition of auxin transport from the epicotyl into the root. This is supported by the observation that spreading of a 0.5% paste with IAA over the epicotyl stump immediately after amputation prevents the mentioned decrease of the gibberellin level in the roots, whereas this decrease is intensified by using a paste with TIBA which inhibits the auxin transport. The results of this work support the possibility of direct gibberellin synthesis in the roots.

The paper deals with the relationship between the glucose utilization and growth ofPenicillium frequentans. The vegetative growth was scanty and sporulation started at a time when glucose was abundant in the culture medium. Occurrence of autolysis in spite of the presence of glucose in the culture medium is a peculiar phenomenon reported here. The autolysing culture gives rise to conditions which favour the germination of spores and the development of vegetative growth. The citric acid is the major metabolite produced by the fungus and its biochemical origin appears to follow condensation of oxalacetate and acetate. Lastly production of citrmin as another metabolite has also been reported.

Both quantitative and qualitative immunochemical methods were used for studying the mutual relationships of several spocies and the subspecies of the genusPhaseolus: Ph. vulgaris L. ssp.vulgaris, Ph. vulgaris L. ssp.aborigineus Burk.,Ph. coccineus L.,Ph. acutifolius A. Gray,Ph. lunatus L. (American endemites) andPh. aureus L. (a typical Asian bean). Protein characters of cotyledons (i.e., "storage" proteins) of the above species were compared with the aid of antisera prepared against seed (cotyledon) proteins ofPh. vulgaris L. ssp.vulgaris, cv. Veltruská Saxa, using
(a) the whole complex of cotyledon protein,
(b) the albumin fraction of this complex,
(c) the globulin fraction,
(d) crystaline phaseolin.
Our results are in agreement with the morphological and genetic data ofBurkart andBrücher on the close relationship betweenPh. vulgaris L. ssp.vulgaris andPh. vulgaris L. ssp.aborigineus (both contain a character designated asPh. vulgaris protein 1 which is lacking in the others, both contain an identical phaseolin and exhibit only negligible differences in the specificity of proteins). The closest to these two species isPh. coccineus (almost identical phaseolin, small differences in the albumin and globulin fractions, a greater quantitative difference in protein specificity).Ph. acutifolius contains a somewhat different phaseolin, exhibits greater deviations in the albumin and globulin fractions and a greater quantitative difference in protein specificity.Ph. lunatus andPh. aureus are quite different in all the above respects. These data are in good agreement with genetic data (crossability).

In both types of crosses (3n C.G.×4n D 154 and 4n D 154×3n C.G.) pods were found to set. In the first case pods shed within 4 days. In the second case pods were found to persist till maturity. Only a few uppermost ovules were found to be fertilized. Pollen tubes were seen to reach the ovules within 24 hours.
In 4n D 154×3n C.G. fusion of sperm with the egg was not noted to be complete till 3 days but the secondary nucleus is fertilized by other sperm. In 3n C.G.×D 154 fusion of sperm with egg or with polars was not complete within 3 days. Signs of degeneration of ovules were noted on the 5th day in both cases.

Mosaic disease ofAnchusa officinalis found at a ruderal association in Prague-Holešovice in the close proximity of TMV infected cruciferous weedsCardaria draba andSisymbrium loeselii, was identified to be caused by the same agent-the necrotic TMV-strain.

Lucerne plants in the first crop year as well as plants of spring wheat from different sites of the respective experimental plots showed differences in sap exudation from detopped roots or from stumps of the main shoots, reflecting differences in properties of the soil profile. The differences in sap exudation were observed at a time when the plants did not show any visible differences in water availability.
Differences in the water potential deficit of the leaf blades of lucerne plants in the second crop year and of sugar beet plants, related to differences in soil profile properties, were observed in another series of experiments. Sugar beet plants showed a higher physiological lability than lucerne plants.
The sites characterized by unfavourable plant-water-relations usually gave lower yields. The coefficients of variability for the yields of lucerne fresh matter from irrigated plots were three times lower than those for yields from plots without irrigation, influenced by soil heterogeneity.

The effects of various cultural factors on the secretion of three pectic enzymes (PP, PG and PE) byAlternaria tenuis on synthetic media were studied. The results can be summarised as follow:
1. No definite correlation between the secretion of pectic enzymes, pH of the medium and the growth of the fungus was observed.
2. The secretion of the enzyme was dependent on the presence of pectin in the medium.
3. While various sugars were found to be equally effective, production of the enzymes was better on a medium without any sugar.
4. After varying the various concentrations and constituents of the medium, the following medium was found to be the best for the enzyme secretion: 1% pectin, 0.2% asparagine, 0.05% magnesium sulphate and 0.3% potassium dihydrogen phosphate.
5. It was established that on the above medium the fungus required four days of incubation at 25°C for the secretion of most active pectic enzymes.

Substances inhibiting local infection with virus X were isolated from leaves of potato cultivars Saphir, Saco, and Blaník by means of ultracentifugation and were concentrated with ammonium sulphate. These inhibitors were effective if rubbed into leaves of some host plants at least 2-4 days prior to infection without using any abrasives.

The calculation and construction of a simple nomogram to be used instead of a set of two equations in a two-wavelength spectrophotometric determination of chlorophyllsa, b, their total amount and ratio is are described. Any pair of equations can be represented nomographically by this construction.

In unseren Versuchen haben wir die Wirkung der 3 isomeren Styrylpyridine und des bekannten Herbizidstoffes 3-Amino-1,2,4-triazols (AT) in der Konzentration 10^-3 m auf die Succinat-dehydrogenase und Succinoxydase-aktivität der Wurzel vonSinapis alba untersucht. Styrylpyridine hommten das SDH-Enzymsystem vollständig, falls sie zum Pflanzenhomogenat noch vor der Messung der Aktivität hinzugefügt wurden. Diese Stoffe zeigten die gleiche Hemmwirkung wie Malonat. In den Versuchen, wo die Pflanzen direkt in den Versuchslösungen kultiviert wurden, zeigte sich 3-Styrylpyridin als das wirksamste; weniger wirksam war 4-Styrylpyridin und am wenigsten wirkte 2-Styrylpyridin. Die gleiche Abstufung der Wirksamkeit lieferten auch die Wachstumsteste und die Untersuchungen der SO-Aktivität. Die Succinoxydase-aktivität war nur wenig beeinflust, falls die Substanzen dem Pflanzenhomogenat beigefügt wurden. Bei den Pflanzen, die in den Versuchslösungen kultiviert wurden, zeigte sich die gleiche Abstufung der Hemmwirkung der SO-Aktivität wie bei dem SDH-System. AT beeinflusste das SO-Enzymsystem überhaupt nicht und das SDH-Enzymsystem wurde im Gegenteil noch stimuliert.

In experiments with fodder cabbage and sugar beet the influences were tested which restrict the finding of a uniform linear dependence between the chlorophyll content and photosynthetic rate. The main factor is most probably the irradiation during the growth of plants and the measuring of photosynthetic rate. Changes in the density and length of irradiation with the proceeding spring season are reflected in the decrease of unit chlorophyll activity in all leaves of the plant. Such differences were not observed in plants grown in winter months at a low greenhouse irradiation density. High irradiation density during the measurement of photosynthesis ensures the finding of high correlation of photosynthetic rate with the chlorophyll amount per unit area of leaf. With a low irradiation density, or in thick leaves, the lower layers of chloroplasts are not saturated with radiation, and hence a higher correlation coefficient is found by relating photosynthetic rate to the percentage of chlorophyll in dry weight than to the quantity of chlorophyll per unit area of leaf blade. In some experiments higher activity of chlorophylls was found in young leaves before they have reached the state of "photosynthetic maturity" than after this turning point. This difference diminished by relating the photosynthetic rate to chlorophylla content instead of the total amount of chlorophylls (a+b). High activity of chlorophylls in very young leaves and great individual variability within the experimental plant groups caused by uneven cultivation conditions are the basis of apparent sigmoid character of average curves for the chlorophyll-photosynthesis relation.

Stimulation and inhibition of photosynthesis inHydrilla verticillata Presl. with quinine sulphate and quinine alkaloid with concentrations ranging between 0.001 and 100 ppm was observed. Quantitative measurements of photosynthesis were done by a microburette (Audus 1940) and qualitative estimations by the modified apparatus byZutshi (1965a). Maximum inhibition of 50% and 34% is obtained with 100 ppm of quinine sulphate and quinine alkaloid respectively. The inhibition is due to the adverse effect on the pigment system particularly on carotene (Zutshi 1963). Forty percent stimulation of photosynthesis is obtained with 0.01 ppm quinine sulphate and 12.5% with 0.001 ppm quinine alkaloid. Difference in the biological activity of these two alkaloids is due to their different chemical structure and purity.

Mycelium of white-rot fungi secretes laccase into the medium. It was found by cultivation on malt-agar plates that the mycelium does not produce laccase equally in all its parts. The youngest hyphae at the margins of the colony represent usually the maximum producers, whereas older hyphae produce less or none at all. An exception here isCollybia velutipes which is the weakest producer of laccase of all the fungi studied and where only the older hyphae begin to secrete it. Manometric estimation of laccase showed that maximum specific activity of laccase is achieved at the boundary between the phases of initial and linear growth and i₁₁ some cases during the first half of linear growth. Ageing of the mycelium characterized by certain changes in its metabolism is reflected in changes of enzyme production by fungal hypha of different age.