The transmission of carrot mosaic virus (CMV) by the crude sap to 11 varieties of plants from 4 families was demonstrated. From these plants the virus could be transferred back to a healthy carrot cultivated from the seed in isolation. The incubation time required for the appearance of the symptoms of CMV was 7-20 days. The plants on which mosaic or spot symptoms appeared on the leaves after transfer by the sap at temperatures below 15°C remains habitually healthy after the transfer of virus at higher temperatures.
The results of the mechanical inoculation of CMV by the crude infectious sap to young carrots cultivated from seeds differentiated this virus fromApium virus 1, which after mechanical inoculation causes chlorosis of the youngest carrot leaves in contrast to CMV. A further differentiation of CMV fromApium virus 1 is shown by the fact that CMV can be transferred only to the familyDaucaceae. It differs in this fromApium virus 1 which is transferred exclusively to this family (Köhler, Klinkowski 1954). CMV is differentiated fromCucumis virus 1/Doolittle Smith by some different host plants.

The amount of energy dissipated in the form of heat in the metabolic processes carried on during the initial period of the germination of wheat seeds was determined directy by means of an adiabatic microcalorimeter. The total energy simultaneously liberated in the respiration of the investigated seeds was calculated from the carbon-dioxide production. The proportion of total energy released in respiration to the amount of energy dissipated as heat indicates that about 5 per cent of respiratory energy is retained in the tissues of growing seedlings. The percentual rate of energy dissipated is not dependent on the temperature or the age of seedlings.

The purpose of this paper is to compare some results achieved in the enzymatic decay of beech wood meal and holocelulose affected by mycelium-free culture filtrate of wood destroying fungusSchizophyllum commune. The fungus had been obtained from the Institute of Plant Physiology, J. E. Purkyně University, Brno.

The relationship of the membrane structure, designated in electron microscopy as the Golgi apparatus, to the classic Golgi apparatus in the light microscope were studied withFagopyrum. Comparison of these structures in plant cells with the same or similar structures in animal cells led to the following conclusions: there exist two groups of formations, impregnable with osmium or silver, considered as the classic Golgi apparatus. The first group contains the active membrane structures. These are the dictyosomes and the anastomosing form of the electron microscopic Golgi apparatus. To this group belongs also the endoplasmatic reticulum, which in plant cells forms dense vacuoles, having the appearance of the classic Golgi apparatus, and in animal cells occasionally has a similar arrangement as the anastomosing form of the Golgi apparatus. The second group comprises formation containing reserve and secretion material, i.e. predominantly products of the activity of the electron microscopic Golgi apparatus and of the endoplasmic reticulum (matter of the dense vacuoles, lipochondria, secretory granula etc.).
In the plant cells, especially ofFygopyrum, the dictyosomes contained in the structures of the first group are separated from the formations of a reserve character in the second group, formed in the lumen of the endoplasmic reticulum (dense vacuoles). The identity of the dictyosomes with the osmiophilic platelets, considered by some authors in the light microscope as the classic Golgi apparatus, has not been proved up to present, because of the one-sidedness of the methods used nowadays. WithFagopyrum no foundation has been observed for the assumed formation of net-form structures by grouping of the dictyosomes. Structures similar to the net-form of the classic Golgi apparatus in the animal cell form only dense vacuoles.
On the basis of the differentiation of both types of formations in the plant cell, the foundations were laid for the characterization of the classic Golgi apparatus in the animal cell. The net-form of the classic Golgi apparatus in the animal cell is obviously not artificial, but reflects the ultrastructural arrangement of the electron microscopic Golgi apparatus or of the endoplasmic reticulum.
The problem of the suitability and specification of the name Golgi apparatus in the animal and plant cell was also discussed. In contrast to the opinion of some authors, it does not appear useful to remove the name golgi apparatus, designating the dictyosomes and the anastomosing forms of the smooth membranes.

The stomata closure in Begonia semperflorens by alpha - rays was studied. Complete closure of the stomata was used as indication of the reaction. The minimal doses with significant results was 2-2. 10⁶ α. cm^-2, the maximum at the dose of approx. 9. 10⁶ α. cm^-2 was found.

Experiments with sunflower and fodder cabbage showed that reversion of the leaf disks lower side upwards (towards the radiation source) decreased the photosynthetic rate by as much as 26% both at full (2. 10⁵ erg. cm^-2. sec.^-1) and half density of irradiation. On placing two disks one on another the photosynthetic rate was decreased in the upper disk in a similar way as it was on reversion even if it were placed in the normal position (upper side upwards). But assimilation in the lower disk was only a fraction (0-40%) of that of the upper disk and in thick leaves was within the limits of the compensation point. The sum of the increase in dry weight in both disks due to photosynthesis exceeds the increment in one normally placed disk only in thin leaves and at high density of radiation. On the basis of the differences found it is advised to discard experimental samples where a quarter of the disks were reversed during exposure. On evaluating samples in which some of the disks were duplicated in error, it is most accurate to deduct the weight of one control disk from the weight obtained. The decrease in photosynthetic rate found in reversed and duplicated disks is evidently due to the simultaneous effect of differences in the supply of CO₂ and radiation energy to the assimilating tissue and apparatus and also to differences in the photosynthetic capacity of different leaf tissues.

In der vorliegenden Arbeit wird die Einwirkung der Humusstoffe durch Besprühen der Zuskerrübenblätter untersucht. Gleichzeitig ist auch die Eignung der Kombination von Humusstoffen und Minerallösung bei der Blattdüngung überprüft worden. Die Versuchsergebnisse lassen sich folgendermassen zusammenfassen: Die Blattdüngung mit Humusstoffen, insbesondere in Kombination mit Mineralnährstoffen beeinflusst das Wachstum der Zuckerrübe günstig. Das Gewicht der Rübenblätter und der Wurzel, sowie der Zuckergehalt werden erhöht. Bei den in Wasserkultur gezogenen und mit einer Nährlösung von vollständigerer Zusammensetzung der Mineralstoffe besprühten Pflanzen ist die Wirksamkeit des Besprühens grösser, als bei den Vergleichsversuchen, deren Pflanzen in Sand mit Nährlösung kultiviert wurden. Bei einer Anwendung am Blatte rufen die Humusstoffe ähnliche Veränderungen des anatomischen Baues der Gewebe und der Organe hervor wie nach ihrer Zugabe in die Nährlösung zu den Wurzeln. Die Humusstoffe, insbesondere in Kombination mit einer Minerallösung erhöhen den Chlorophyllgehalt und die Intensität der Photosynthese in den Zuckerrübenblättern. Die Blattdüngung mit Humusstoffen erhöht gleichzeitig auch die Transpiration der Zuckerrübe.

It was observed that the polyploids ofTrigonella foenum-graecum produced by seed treatment with 0.2% colchicine died after two cotyledonary stage, while the ones produced by seedling treatment survived. The root and shoot of seed treated plants were found to be mixoploids. The root tips exhibited 2n to 12n chromosomes and with the passage of time there is a regular decrease in the frequency of cells with lower chromosomes. The frequency of dividing cells decreases considerably towards the end of the 6th day due to the highploidy of most of the ploid plants. In case of seedling treatment the first formed tissue was mixoploid of high level similar to that of seed treated ones but in some cases the growing tip reverted to low level of ploidy which lead to more or less normal growth.
Since the difference in the constitution of seed and seedling treated plants lies in their root system, it has been suggested that probably highploidy of root system in the former may be responsible for the 100% mortality of plants.

Die vorgelegte Arbeit befasst sich mit der gegenseitigen Beziehung zwischen Roggen und Hanf in Wasserkultur bei ergänzter Mineralernährung. Nach 24tägiger Kultivierung wurden keine beweiskräftigen Unterschiede des Wachstums der Kontrollpflanzen und der Mischkultur gefunden. Beweiskräftige Unterschiede wurden jedoch in der H₂PO₄-Ionensorption bei Anwendung des Radioisotops³²P festgestellt. Beeinflusst wurde auch der Wasserbedarf der Pflanzen in der Mischung. Die festgestellten Unterschiede wurden durch die Wirkung von spezifischen Stoffen in den Wurzelausscheidungen der beteiligten Pflanzen erklärt.

The exposure ofTaraxacum officinale L. at flowering time to a weak magnetic field resulted in (1) retarded opening and the closing of the inflorescence, (2) wilting and death after prolonged exposure. Controls were unchanged. Plants exposed to the effect of magnetic fields were degenerated in subsequent year.

Experiments with isolated wheat roots and with intact wheat plants showed that glutamic acid decarboxylase from the roots takes part in the transformation of substance in the medium and that its activity is influenced by the medium. Glutamic acid decarboxylase is thus a factor taking part in the formation of substances excreted by the plants roots.

The rather equal development of the two cotyledons determines the bilateral symmetry in the pea seedling, just as their unilateral position results in the dorsiventrality of the epicotyl and root. The morphogenic manifestation of the symmetry relations conditioned, in the first place, by a different distribution of auxin out of the cotyledons may be enhanced by means of exogenous growth regulators, particularly IAA, GA₃, and TIBA.

Cultures of the coenobial four-celled chlorococcal algaScenedesmus quadricauda were synchronized. Ontogeny of the species, proceeding analogously to that of the unicellular forms, was studied; however, the cells in the coenobium ripen successively. The paramoters of the synchronized cultures were followed and according to the obtained results an objective method of evaluation of the synchronization-degree of the algal cultures, on the basis of information theory, was suggested.

Einige durch Chloroalhydrat behandlung erzielte mixoploide Wurzelspitzen vonVicia faba verzweigen sich dichotomisch und es hat sich herausgestellt, dass die Dichotomie in jenen Wurzeln vor sich geht, welche einen polyploiden axialen Strang, der bis in das Transversalmeristem hineinragt, enthalten. Zu beiden Seiten dieses Streifens differenziert sich durch entsprechend orientierte Zellteilungen je ein neues Transversalmeristem. Wenn der polyploide Streifen nicht axial verläuft, so spaltet sich die Wurzelspitze in einen stärkeren weiter wachsenden und einen schwächeren, meist sein weiteres Wachstum einstellenden Teil. Da sich die polyploiden meristematischen Zellen in einem diploiden Gewebe als fremde Elemente verhalten können, was sich in den häufig vorkommenden Chorisen äussert, so kann die Dichotomie der mixoploiden Wurzelspitzen durch eine Schwächung der normalen Korrelationen zwischen den Initialzellen erklärt werden, ähnlich wie wenn die Wurzelspitze durch einen medianen Längsschnitt angeschmitten wäre. Da werden, wie seinerzeitLopriore (1896) gezeigt hat, die beiden Hälften der Wurzelspitze restituiert und wachsen als zwei selbständige Wurzeln weiter. Verläuft der Einschnitt nicht median, so stellt der schwächere Teil der Wurzelspitze sein Wachstum früher oder später meist ein. Normal dichotomisch sich verzweigende Wurzeln tun das ohne auslösende Wirkung polyploider, axial verlaufender Zellstreifen.

Mittels unmittelbarer Analyse auf Grund chemischer Reaktionen, Chromatographie und elektronenmikroskopischer Diffraktion wurden beiNitella sp. im Zellsaft drei organische Säuren festgestellt: Weinsäure, Zitronensäure und eine Säure, deren Identifizierung bisher nicht gelungen ist. Weiter wurde festgestellt, dassNitella-Zellen, die einen langsameren Metabolismus haben oder ein höheres pH des Zellsaftes aufweisen, Neutralrot in ihren Vakuolen viel langsamer ansammeln als Zellen unter normalen Bedingungen. Eine Blockierung der Atemenzyme durch Kyanwasserst off hat aber keinen Einfluss auf die Geschwindigkeit der Aufnahme dieses Farbstoffes durch die lebenden Zellen.
Auf Grund der Ergebnisse dieser Arbeit ist die Annahme möglich, dass die Aufnahme basicher Parbstoffe durchNitella auf Grund eines Ionengefälles vor sich geht und dass seine Geschwindigkeit unmittelbar von der Konzentration organischer Säuren im Zellsafte beeinflusst wird.

The given data shows that between the halves of lateral leaflets ofMedicago sativa there exists an anatomical symmetry of the epidermis as well as in the case when both lateral leaflets are compared one with another. In spite of several differences, which may be caused by the environmental conditions, the analysis of variance shows that these differences have no importance in the total variability of obtained data.
Similarly, the symmetry was shown by the study of water loss of the pairs' lateral leaflets. In this case the total course of the water loss curve must be appreciated, which is the same in the curves of a leaflets' pair of the same leaf. Differences in the absolute water loss are caused probably by the manipulation with the material before the experiment.

Cyanus segetum LAM. was transferred from a long to a short photoperiodic regime at various stages of ontogenesis and the development of the plant investigated. The morphology of the leaves ofCyanus segetum was dependent on the photoperiodic regime. On a short photoperiodic regime, pinnately sected leaves were formed, but only if development was inhibited while the shoot apex still had a structure characteristic for the vegetative plant. The ability to influence the shape of the leaves by a short day ends before the morphological differentiation of the inflorescence at the time of the disappearance of the vegetative structure and the formation of the meristematic mantle. After this time all leaves were smooth-edged like those of the controls on a long day. Although the ability to influence leaves was limited to the period of initiation of the leaf primordia, it was not restricted to the primordia then being initiated. The conditions of development also affected leaves whose primordia had already been initiated. This was evidently due to the action of photoperiodic conditions via ontogenesis. The position of the axils was also changed in dependence on the photoperiodic regime.

Es wurde nachgeforscht, ob es vielleicht in den Blüten vonGagea lutea Vorrichtungen gibt, welche eine Polyspermie, d. h. eine Befruchtung durch mehrere Pollenschläuche zu verhindern vermögen. Das Peristom des Eichens liegt vor der Befruchtung der Fruchtknotenwand da an, wohin der Pollenschlauch durch das drüsige Leitgewebe geführt wird und in die Mikropyle eindringt. Wenn nachher der Befruchtungsvorgang vollbracht wird, so verlängert sich bei den meisten Eichen ihr Funiculus an seiner Basis, wodurch das Peristom von der Fruchtknotenwand entfernt und in die Mikropyle kein Pollenschlauch mehr geführt wird. Auch ist jetzt die Mikropyle durch den Pollenschlauch verstopft. Das unbefruchtete Eichen scheidet irgend welche Substanz aus seiner Mikropyle aus, durch welche die Pollenschäuche chemotropisch angezogen werden. Einige wenige Eichen reagieren jedoch nicht nach der Befruchtung durch ein Wachstum des Funiculus an seiner Basis und das Peristom wird von der Fruchtwand (Plazenta) nicht entfernt. Das schoint jedoch nur eine Ausnahme zu sein.

Es wird der Aufbau und die Arbeitsweise eines motorisierten und mit URAS-Geräten für CO₂ und H₂O ausgerüsteten Feldlabors beschrieben. Die wichtigsten Voraussetzungen für den Einsatz der URAS-Instrumentarien im Freiland sind ein geländegängiges Fahrzeug, in das alle empfindlichen Geräteteile federnd montiert sind, Stromzufuhr ausreichender Frequenz-und Spannungskonstanz und eine ausreichende Temperaturisolation der Fahrezugaussenwände. Ausserdem ist das URAS-Instrumentarium in einen thermostierten Schrank einzubauen und das Fahrzeug während der Messungen am Standort fest mit Stützen zu arretieren, um Erschütterungen der Registriereinrichtungen zu vermeiden. Die empfindlichsten Geräteteile müssen ausgebaut und möglichst erschütterungsfrei transportiert werden.
Weitere technische Einzelheiten werden erörtert und spezielle methodische Probleme zur Ausschaltung der Übertemperaturen in den Küvetten diskutiert.

Die Arbeit behandelt die gegenseitige Beziehung zwischen Hanf und Roggen in Wasserkultur bei nicht ergänzter Mineralernährung. Nach 18-tägiger Kultivierung in Nährlösung mit³²P wurden beweiskräftige Phosphorsorptions- und Transpirationsdifferenzen zwischen den Kontrollpflanzen und der Mischung gefunden. Die Hanf-Kontrolle verbrauchte in 18 Tagen 85,5% Phosphor, Hanf in der Mischung 94%, die Roggen-Kontrolle 95,3%, Roggen in der Mischung 106,7% auf je eine Pflanze umgerechnet. Das Wachstum wurde nicht beeinflusst. Die Ergebnisse lassen sich nicht bloss durch Nährstoffkonkurrenz zwischen den beteiligten Arten, sondern durch die Anwesenheit eines weiteren Faktors erklären.

Mit Ultrarot-Absorptionsschreibern für CO₂ und H₂O wurden die apparente Photosynthese, die Respiration und Transpiration von Maispflanzen und-blättern unter konstanten Bedingungen untersucht.
Zwischen den 3 geprüften Sorten, "Schindelmeiser", "Siloma" und "WIR 25" ergaben sich keine signifikanten Sortenunterschiede hinsichtlich der apparenten Photosynthese obwohl sich die Sorten-bedingt durch die unterschiedliche Vegetationsdauer-in den Erträgen deutlich unterscheiden; die Einzelpflanzenstrenungen innerhalb der Sorten lagen bei 25%.
Bei fast gleich grosser Einzelpflanzenstreuung innerhalb der Sorte zeigte sich eine signifikant
Bei fast gleich grosser Einzelpflanzenstreuung innerhalb der Sorte zeigte sich eine signifikant höhere Transpiration bei "WIR 25" als bei den beiden anderen Sorten. Die höchste apparente Photosynthese wiesen die Blätter auf, die dem Kolben am nächsten inseriert waren (4.-5. Blatt).
Die CO₂-Aufnahme je Blattfläche und Stunde war bei den verschiedenen Abschnitten des Blattes unterschiedlich; im Mittelteil wurden signifikant höhere Werte als im basalen Teil der Blattspreite beobachtet. Die CO₂-Aufnahme korrelierte positiv mit der mineralischen Ernährung.
Es gab keine Unterschiede in der CO₂-Aufnahme bei den Pflanzen ohne und mit Kolben. Bei Pflanzen ohne Kolben können die produzierten Assimilate (Saccharose) nicht gespeichert werden; sie überschwemmen deshalb die ganze Pflanze und werden zu einem grossen Teil nachts veratmet. Der effektive Stoffgewinn an Trockenmasse dieser kolbenlosen Pflanzen erreicht nur 70% von denen mit Kolben.

Agar-gel electrophoresis was used for studying the protein fractions of apple-tree blossom and leaf extracts and some qualitative differences were found. The finding is discussed in connection with flower-bud differentiation.

Plants of ten varietal populations of maize and their progenies in S₃ generation had been evaluated for their resistance to sources of corn smut in conditions of increased infection level. According to the infection degree, the experimental material was divided into classes (I-V) corresponding to five categories of resistance.
The relative representation of progenies from populations differing in their susceptibility to the parasite in their particular classes showed that the heterozygous varietal populations posses some imunological structure.
1. In the composition of the populations the resistant forms prevail over the susceptible ones. In the populations studied 82.8-98.5% dissected at selfing were grouped into classes I-III.
2. The basis of resistance of populations is formed by a group of forms ranged into the second class of resistance. This group being equally represented in all populations (31.1-40.8%) independently of their susceptibility to corn smut.
3. The differences in disease attack of plants of the particular populations had been influenced by the relative participation of selfed progenies, ranged on the one hand into class I and on the other hand into classes III and IV. The occurence of progenies in these categories in populations arranged consecutively from higher to lower resistance varied in conformity on extent 46.2-15.5%, 11.5-37.5% and 1.5-17.8%.
The experimental data showed, among others that the general smut attack of plants in populations (23.5-49.6%) corresponded in most instances to the average attack of progenies in S₃ generation (21.0-44.2%).

Whereas experiments directed towards proving the infectious character of the hop curl disease did not give reliable proof of its virus character (we have not been able to transfer it neither by cuttings nor by graft), but made possible its differentiation from the English nettlehead hop virus disease, the practical experiences and results presented in this paper show that nutritional conditions essentially affect the known variability of the external manifestations of the hop curl disease. Especially such nutrients play a role which with the normal fertilising techniques are not returned to the soil in sufficient quantity. Since the hop curl disease was noticeably inhibited in a nutritional field experiment on application of the salts of some elements, predominantly of B, Mg, Mo, Mn, Ni, I and Zn, it appears possible to apply "symptomatic therapy" of the hop curl disease, which could have wide practical importance for limiting this disease.
In order to supplement the provocation field experiments, comparative investigations of the chemical composition of the leaves from healthy and hop curl diseased plants were carried out. Quantitative analysis of the biogenic elements carried out by the usual methods and by polarography showed a regularly higher content of P, K, Ca and a lower content of Zn in the diseased plants as compared to healthy ones. The differences observed in the content of N, Na, Mg, S, Fe and Cu were not always in the same sense. Chemical analysis was accompanied by parallel spectral analysis of ash. This made it possible to obtain a considerably complete survey of the qualitative and approximately quantitative representation of a whole series of other elements in healthy and diseased plants; however, no characteristic differences were recorded.
Finally the results obtained in the present work are confronted with the findings of other researches, especially from Germany, and discussed.

1. In tetraploid Phaseolus sp. × P. calcaratus cross, shrivelled but viable seeds were produced. One hybrid was raised but it died within a month. Another hybrid was raised to flowering by artificially culturing the embryos before shrivelling.
2. The F₁ of tetraploid Phaseolus sp. × P. calcaratus cross, had various leaf abnormalities at an early stage. In most of the characters the hybrid was intermediate between the two parents. The twining habit of P. calcaratus dominated in the hybrid. The F₁ plant had 10.7 per cent pollen fertility. The hybrid died within a week of flowering.
3. In P. calcaratus × tetraploid Phaseolus sp. cross, rudimentary, non-viable seeds were produced.
4. The incompatibility barriers are active - (a) at post-fertilization stages causing shrivelled and rudimentary seeds and (b) in the F₁ generation causing hybrid lethality and sterility. The importance of embryo culture techniques in removal of the first type of crossability barriers is stressed.