Es wird über laufende Arbeiten berichtet.-Bei virösen Erkrankungen gehen dem Auftreten äusserlich erkennbarer Symptome cytologische Veränderungen voraus. Als solche werden u. a. charakteristische Zelleinschlüsse in jungen Keimen von Kartoffelknollen beschrieben. Mit ihrer Hilfe lässt sich nachweisen, dass viröse Prozesse auch in "gesund" getesteten Knollen vorkommen können.-Das unterschiedliche Auftreten spindelförmiger Zellkerne im Palisadenparenchym der Blätter von Solanum tuberosum wird als Zeichen verschieden stark ausgeprägter Neigung zu viröser Erkrankung (Virophilie) angesehen. Versuche zur chemisch-physikalischen Induktion viröser Prozesse ergaben ein bemerkenswertes Auftreten derartiger Kernformen in behandelten Pflanzen.-Die Virogenese wird als ein im Wesentlichen physiologischer Prozess aufgefasst, den die Pflanze gestaltet und der sich sowohl post infectionem als auch autonom entwickeln kann. Das anatomisch nachweisbare Vorkommen virogener Mikroprozesse und viröser Mikroherde macht den Nachweis, dass eine Pflanze virusfrei ist, unmöglich. Vielmehr ist mit der Ubiquität dieses Vorkommens zu rechnen.

From the partial results of artificial cultures in the presence of pistil tissue-pulp the author draws the preliminary conclusion that the inhibitory factor in the pistil ofNicotiana alataLink etOtto is already present before pollination.
These questions were investigated by means of artificial cultivation of pollen tubes on agar in the presence of compatible and incompatible pulped pistils which had been previously prepared in various ways.
This report gives the results of the last series of experiments (part A in the scheme). In the series of earlier experiments no signs of any marked inhibition were recorded.

The study of physico-chemical properties of protopectinase secreted by R. solani was for the first time made and recorded in this paper. The results can be summarised as follows.
1. Protopectinase preparation killed the cells even before maceration was completed.
2. Dilution with water and with autoclaved enzyme solution reduced macerating activity less than toxicity, and thus, indicated that toxins other than enzymes were present in culture filtrates.
3. Protopectinase was highly thermolabile as activity was completely lost after heating for 5 minutes at and above 60° C. When the enzyme was stored at 25° C. for 15 days, there was 80% loss of activity.
4. Protopectinase activity and toxicity was highest at pH 3-4 and there appeared another optimum at pH 7.4.
5. A slight loss of activity occurred on dialysis and was slightly restored by the addition of an autoclaved undialysed enzyme solution. Another peculiarity of the dialysed enzyme solution was that it was most active at pH 6.8 and less active at pH 3.5.
6. Protopectinase was more readily precipitated with acetone than with ethanol. The toxicity of the solution of the precipitate was less than what would have been expected. This again indicated that toxic substances, presumably not enzymic, were removed during the partial purification by precipitation.
7. The addition of monovalent and bivalent salts, particularly in high concentration, to the protopectinase solution resulted in some loss of activity; there was a greater loss with bivalent salts. But soaking test tissue in the salt solutions did not have any effect on protopectinase activity.

1. The aim of the present paper was an investigation of pollen grain size of different species of the Triticum L. natural polyploid series.
2. We determined the pollen grain size of 15 specimens belonging to 8 species. The determination was carried out on permanent acetocarmine preparations.
3. The pollen grain size of differentTriticum species tends to grow with the increasing number of chromosomes. The following mean volumes were computed for the different groups: 62.10³ μ ³ for the diploid group, 96.10³ μ ³ for the tetraploid group (of which 73.10³ μ ³ forT. timopheevi Zhuk.), and 118.10³ μ ³ for the hexaploid group.
4. As can be seen, the volume of the pollen grain does not represent a corresponding multiple of the chromosome number. The reason for this disagreement with the theoretically expected linear relation between the chromosome number and the pollen grain size lies apparently in the allopolyploidy of the polyploid series of the genusTriticum. It seems that the genetically different genoms A, B, D, and G also exert a different effect on the pollen grain size.
5. Our calculations show genom B to have 62%, genom D 29%, and genom G 18% of the effect of genom A (100%). These genoms form a sequence A>B>D>G with respect to their effect on pollen grain volume.

Weder die Dominanzverhältnisse zwischen den Sprossanlagen noch die Regulationswirkungen der Laub- und Keimblätter, die unter anderem für die vorzeitige Wachstumssistierung namentlich bei den Holzgewächsen verantwortlich sind, lassen sich durch Gibberellinsäure verändern. Doch setzt GS die von assimilierenden Blättern und vegetativen Speicherorganen ausgehenden Hemmungen herab und ersetzt in dieser Hinsicht die Stimulationswirkungen der Wurzeln, allerdings nur unvollständig, da es nachher zu den bekannten Ernährungs- und Gestaltungsstörungen kommt. Auf die Knollenbildung wirkt GS ungünstig, da die Terminalknospe der Knollenanlage zu starkem Streckungswachstum statt zu erforderlicher Ruhe gebracht wird. Die günstige Wirkung von GS auf die Blütenbildung bei der LangkurztagpflanzeBryophyllum crenatum tritt nur dann ein, wenn die mit GS behandelten Kurztagrosetten noch weiter im Kurztag gezogen werden. Somit kommt es hier mehr auf die phylogenetische Anpassung dieser Pflanzen an die Tropen, als auf gewisse stoffliche Einflüsse an, was mutatis mutandis auch von der Rhythmik der Bäume gilt. *** DIRECT SUPPORT *** A01GP005 00005

A description is given of the production of two types of chimera between tomato and nightshade (Solanum koelreuterianum Winkler andS. geartnerianum Winkler).
In the case ofS. gaertnerianum the micromorphological and anatomical characters showed no signs of the significant specific reciprocal effect of one tissue on the other.
The seed progeny of theS. gaertnerianum chimera resembled the control nightshade plants in all the characters investigated.
The following characters were studied: Size of stomata, shape of stomata, shape of trichomes, fruit epidermis, section through the petiole, section through the leaf blade and number of seeds.

Humus acid (Humussäure Riedel de Haen AG. Seelze Hannover) in 0.01% concentration increases the respiration intensity of plant roots grown in water cultures both as regards O₂ consumption and CO₂ production, while RQ (CO₂:O₂) is only very slightly increased. The plants used in these experiments were the winter wheat Pyšelka (Triticum vulgare Vill.), maize Zaj íček's "Český koňský zub" (Zea mays L.) and the gourd Veltrusská velkoplodá (Cucurbita maxima L.). O₂ consumption and CO₂ production were determined on separated root tips by the direct Warburg method. It was found that the effect of humus acid is not only to increase respiration intensity in the roots of the experimental plants, but also their lengths and dry weights (for all experimental plants); for maize and gourd the dry weights of overground parts were also increased, which indicates that increased respiration intensity was linked with more intensive growth of the plants.

In a previous communication (Bartoš, Kubín andŠetlík 1960) a method was reported, which makes it possible to measure the average rate of photosynthesis in a representative sample of a large number of leaves. The sampling is made by cutting out disks of leaf tissue, following a definite pattern. Isolated leaf disks are then illuminated under controlled conditions and the rate of photosynthesis is estimated by weighing the increment of dry matter in a given time interval.
Data published in the present paper demonstrate that this method can be successfully used for a characterisation of photosynthetic capacity (specific rate of photosynthesis, seeBartoš, Kubín andŠetlík 1960). Both specific values for individual plants and average values for homogenous plant populations may be estimated with very good accuracy. One of the chief factors which render this possible is obviously the surprising homogeneity of the photosynthetic tissue of leaves. Samples of very small size may serve as representative of a large total leaf area, e.g. of a population under field conditions.
Preliminary results of comparative investigations suggest that, with the plant varieties examined, differences in photosynthetic capacity are not very great, both between and within populations of diverse varieties. Differences as large as 50% have been encountered so far solely between values of photosynthetic capacity estimated for individual plants in a population. On the other hand, values of average photosynthetic capacity in populations of crop plant varieties within one species or genus are, as a rule, not very distinct and quite often no statistically significant difference can be demonstrated in such cases. Even if the varieties belong to different genera, differences in photosynthetic capacity in their populations greater than some 50% have been found only as an exception.
In considering all these results one important fact must be taken into account, i.e. the intensity of illumination in the apparatus. Contrary to what was intended and awaited, the radiation intensity used was not high enough to saturate photosynthesis in leaf disks. The light dependence of photosynthesis in isolated portions of leaf tissue apparently has a somewhat different character from that usually assumed for intact leaves of higher plants.

A characteristic feature of the effects of humic acids on plant growth is the stimulation of growth in length of the roots. This is sometimes explained as being due to the auxinoid nature of the acids.
The author has examined this assumption by testing segments of wheat coleoptiles and of flax hypocotyls. The growth of segments of both types remained unchanged in solutions of potassium humate in concentrations of 10^-1 to 10^-7 g./l. as compared with the controls in water.
A study was also made of the interaction of humic acids with auxins. The growth curves of segments in concentrations of auxin up to about 20 mg./l. (flax) or 50 mg./l. (wheat) were not altered by the presence of a 10^-1 g./l. concentration of humate in the test solution. With higher concentrations of auxin the growth of the segments in auxin-humate solutions was considerably greater than in solutions containing auxin alone. The effect decreased with rising concentrations of auxins (β-indoleacetic acid and α-naphthylacetic acid).
The auxinoid character of salts of humic acids in water solution was not established, nor was there any confirmation of competitive antagonism in the sense of the antiauxin conception.

The spraying of 26-day-old sunflower plants with a solution containing 50 μg. gibberellic acid/ml. brought about morphological changes in leaves and a statistically significant increase in the leaf shape index (length: width of leaves). The number of leaves on the stem also increased, together with a rise in the value of the ratio of dry weight of stems to dry weight of leaves.

1. In C. olitorius ♀ × C. sidoides ♂, the pod set was 29.4 per cent and the percentage of pod harvested (out of the set pods) was 20 per cent. All harvested pods were empty.
2. In C. sidoides ♀ × C. olitorius ♂, the pod set was 26.8 per cent and that 9.0 per of the cent pods were harvested. The single harvested pod yielded the following types of seeds-4 empty seeds, 9 partially full seeds and 4 apparently full seeds. The apparently full seeds were underweighed. All seeds were non-viable.
3. The pod sets in C. capsularis ♀ × C. sidoides ♂ and in its reciprocal were 31 per cent and 20.0 per cent respectively. No pod remained till maturity.
4. These three species are phylogenetically wide apart.

1. It was found that fluoride has a more pronounced inhibitory effect on the respiration of wheat leaves in plants grown in a solution of gibberellic acid than on that of control plants grown in water, during the entire development of the first leaf.
2. Respiration is markedly inhibited even in old leaves of gibberellintreated plants while the respiration of equally old control plants is stimulated by fluoride by 10-100%.
3. It is assumed that the shift in the equilibrium of respiratory pathways to glycolysis, as is indicated by respiration experiments, is associated with the growth effect of gibberellic acid.

During investigation of amylase activities as continuously variable biochemical features it was found that they are very sensitive to changes in the intensity of vegetative factors. The results of analysis of variance indicate that these characters not only tend to be inheritable themselves, but also the nature and intensity of their reactions to changes in the agro-ecological factors of the external environment show a similar tendency. The actual expression of these features in individuals belonging to a genetically homogeneous group must be considered as the resultant of all reactions of the realisation process concerned, on stimulatory and inhibitory influences, both internal and external. For the genetical analysis of hybrid groups it is necessary to have the most complete picture possible of this continuous modificability which masks the actual genetical variability.
The results obtained in the present investigation provide evidence of complicated relations involved in the hereditary nature and formation of the features under consideration. In further work on the later generations of reciprocal and back crosses it will be necessary to determine more exactly the relative participation of nuclear and plasmatic components both in the hereditary transmission and in the actual formation of these characters.
The present results, although they are only preliminary, confirm the correctness of the modern view in genetics that genetical analysis should be linked with physiological analysis.

Im vorliegenden Beitrag ist eine einfache Methode der Aufklatschchromatographie für die Bewertung des Zuckergehaltes in der Trockensubstanz der Aufklatsche (Aufklatschmasse) beschrieben. Diese Methode ist zum Zwecke der Verfolgung des Spiegels der einzelnen Zucker in den Wurzelspitzen des Weizens ausgearbeitet worden, der in Kulturen mit Humussäurezusatz bei verschiedener relativer Luftfeuchtigkeit wuchs. In der vorliegenden Arbeit ist er am Beispiel der Glukose, unter den Bedingungen niedriger, relativer Feuchtigkeit klargestellt worden. Der Glukosegehalt sinkt mit der Entwicklung der Pflanze bis zum Eintritt der Phase des zweiten Blattes. Während er in der Phase des ersten Blattes bei der Variante mit Humussäure grösser ist, ist dies in der Phase des zweiten Blattes bei den Kontrollpflanzen der Fall,

The part of the radioactive fractions of humus substances which is soluble in alcohol (or in ether) spreads from drops of solution or from a mixture with lanoline paste mainly through the vascular bundles. The active component of humic acid evidently does not spread in the leaves, while the active component of fulvic acids fails to penetrate the tissues of some plants, but in others spreads to a distance of several centimetres.

1. The classical cytological methods, cytochemistry and electron microscopy were used to study the cytoplasm ofFagopyrum esculentum Moench. 2. Cytochemical investigation of inclusions resembling the Golgi apparatus was possible after fixation in Ca-formaldehyde and embedding in carbowax. 3. A characteristic of the inclusions was drawn up. The inclusions resemble some pigment substances of animal cells cytochemically (lipopigments, phenolic pigments). 4. Conditions of staining inclusions with basic dyes, Sudan black B and the PAS reaction were studied. 5. A functional investigation revealed a cycle resembling that known in the formation of secretions in animal cells. 6. The Golgi apparatus and inclusions resembling it appear under the electron microscope as two distinct components.

On a traité des graines d'orge à différentes fréquences ultrasonores (30, 80, 570, 720, 960 kHz) avec des puissances de 2 à 5 W/cm², de 5 à 25 minutes, en vue d'étudier le mécanisme d'action des ultra-sons sur le processus de la germination.
A cet effet, nous avons effectué des enregistrements microcalorimétriques au laboratoire de Monsieur le ProfesseurE. Calvet à la Faculté des Sciences de Marseille, en vue de comparer les courbes représentant la cinétique de la thermogénèse dans le cas des graines traitées ou non traitées par les ultra-sons.
Les courbes montrent que la durée de la thermogénèse physico-chimique caractérisée par la première pointe exothermique est diminuée dans le cas des graines traitées et que le phénomène passe alors rapidement de la phase physico-chimique à la phase de thermogénèse biologique, la deuxième phase pouvant même se superposer à la phase physico-chimique.
Ainsi le traitement provoque une accélération de la germination et modifie favorablement la durée de celle-ci (thermogénèse biologique plus active). Le phénomène d'accélération de la germination se manifestant de la même manière sur des graines dont la thermogénèse fut étudiée plusieurs semaines et plusieurs mois après le traitement aux ultra-sons, cela montre que cette action est irréversible et correspond principalement à une modification de la perméabilité des membranes. Il est cependant possible qu'il vienne s'y associer des actions dépolymérisantes (Prat, Calvet 1945) (dépolymérisation de l'amidon en dextrine) qui expliqueraient, mieux que la seule absorption d'eau, la prolongation dans le temps de l'accélération de la croissance (diminution de la phase endothermique et accélération de la phase exothermique).
Ainsi la thermogénèse des graines traitées aux ultra-sons, grâce à la grande précision de la méthode microcalorimétrique, nous montre que la pénétration ultérieure de l'eau dans les graines, ainsi que les processus enzymologiques produisant la thermogénèse biologique, sont nettement accélérés par les ultra-sons.

The levels of l-ascorbic acid, dehydroascorbic acid and of the bound form of vitamin C were investigated in the tissue from the vicinity of eyelets of dormant potatoes after treating the tubers with ethylene chlorhydrin. During the first week after exposure the l-ascorbic acid level does not change, significantly while the dehydroascorbic acid level decreases markedly. This decrease persists even during the following weeks and returns to normal only on the fourth week after treatment. The l-ascorbic acid level displays a decreasing tendency but a marked decrease may be observed only during the fourth experimental week. The level of the bound form of vitamin C does not change significantly for the whole duration of the experiment.
It can be concluded on the basis of the results obtained that ethylene chlorhydrin deeply affects the oxidation-reduction systems of the potato cell, among other possibilities by disturbing the equilibrium of the important oxidation-reduction system formed by l-ascorbic and dehydroascorbic acid. The bound form of vitamin C does not appear to play a significant role in the process of sprouting.

1. The growth rate of apple pollen tubes at a temperature of 25°C in 10% sucrose solution, with or without boron (0.001% H₃BO₃), shows a practically linear relation to time for 6 hours;Nicotiana alata pollen tubes, which are slower in growth, show a decrease in growth rate after 10 to 15 hours.
2. The greater part of the sucrose in the culture solution is inverted by the pollen tubes. The rate of this reaction increases with time until the substrate is exhausted. When the sucrose concentration drops to 5%, chiefly as a result of the inversion process, the growth rate of the pollen tubes decreases.
3. The growing pollen tubes absorb sucrose from the culture solution. Exogenous utilization of sucrose was evident in the case of apple pollen after 3 hours, inNicotiana pollen after 6 to 8 hours of incubation.
4. In view of the close correspondence between the decrease in the intensity of sucrose absorption by the pollen tubes and the decrease in their growth rate, it may be concluded that the accumulation of callose in pollen tubes while their growth rate is decreasing is not due to any rise in the proportion of glucose not utilized for cell-wall formation. Further, if no change in the glucose: fructose ratio is observed in the culture solution at the time when pollen tube growth is slowed down, it follows that reduction in growth rate and increase in callose accumulation is most probably accompanied by a drop in respiration of glucopyranose component of the absorbed sucrose.
5. Boron encourages sucrose absorption proportionally to the stimulation of pollen tube growth. It is, therefore, possible that the stimulatory effect of boron on growth is connected with carbohydrate metabolism. In view of the fact that pollen tube growth is accelerated by boron at the time when the tubes are still drawing to a great extent or exclusively on the reserve substances in the pollen grain- and in view of the well-known stimulatory effect of boron in distilled water - it follows that the main factor is not necessarily the translocation of carbohydrates into the pollen tubes, but that it is rather a question of the rate of their metabolism.

The term "equivalent evaporation power" is suggested to denote the evaporation power of the atmosphere measured as the relative evaporation from an evaporimeter which resembles to a great extent the physical conditions occurring during transpiration of a plant leaf (e.g. the Piche evaporimeter).
The height dependence of equivalent evaporation power at heights between 5 and 500 cm. in an "open area", in a field of sugar beet, maize, in a mature deciduous wood, in its small circular rejuvenation clearing and on a great clearing was investigated. The higher the absolute values of evaporation the lower the height gradient which is obviously observed to decrease progressively with height in all cases (Figs. 1 and 2). The stands decrease the average equivalent evaporation power in the height interval exceeding their height. Differences between the relative values of equivalent evaporation power of atmospheric environment surrounding different leaves of one plant are frequently considerably higher than those between ecoclimatically completely distinct localities (e.g. between a forest stand and a clearing).
A statistically significant positive correlation was found to exist between the gravimetrically determined all-day total of transpiration of seedlings ofFagus silvatica L. andAcer platanoides L., freely exposed in small lysimeters for the entire vegetation season and between the all-day total of equivalent evaporation power. For the number of days n=95 the mean correlation coefficient r was +0.58±3.0.031 for the beech and +0.56±3.0.046 for the maple. The regression coefficient, which is linearly proportional to the leaf area, was low and provides evidence for the biological regulation of transpiration.
It was shown by simultaneous measurements of transpiration (gravimetrically) of leaves ofSyringa vulgaris L. (n=95) and of equivalent evaporation power at the height of 10, 50 and 150 cm. above the ground in an "open area" that the height gradient of equivalent evaporation power of the atmosphere under natural conditions affects the intensity of transpiration at different heights (Fig. 3).
The observed facts are undoubtedly to be associated with the formation of the xerophytic or mesophytic character of leaves located at different levels of the same plant, and thus withZalensky's law.

1. Die z. T. experimentelle Analyse des Blumenbesuches zweier Syrphiden-Arten (Tubifera pendula L., Syrphus balteatus Deg.) an Parnassia palustris L. unter besonderer Berücksichtigung von Tieren, die mit den Blüteneinrichtungen dieser Pflanze nicht vertraut waren, ergab, dass die "Scheinnektarien" der Blüten für die Fern- und Nahanlockung bedeutungslos und demnach für die Bestäubung entbehrlich sind.
2. Die vorliegenden Untersuchungen ergänzen meine frühere Analyse des Blumenbesuches der genannten zwei Syrphiden-Arten an Parnassia (Daumann, 1932, 1935), die unter vorwiegender Berücksichtigung von Tieren ausgeführt wurden, die mit den Blüteneinrichtungen dieser Pflanze bereits vertraut waren.
3. Meine Ergebnisse bestätigen nicht die AnsichtKuglers (1951), dass die "Scheinnektarien" von Parnassia palustris blumenbesuchende Fliegen "täuschen" und unter umständen die Besuchs- und Bestäubungsaussichten erhöhen können.

Für die Versuche haben wir die Maissorte Hodonínský koňský zub žlutý verwendet. Die vorgekeimten Getreidekörner wurden in fünf verschiedenen Dichten in die mit Sand gefüllten Mitscherlich-Gefässe ausgesäht. Jede Serie wurde fünfmal wiederholt. Die Maispflanzen wurden 21 Tage lang kultiviert. Es wurden Veränderungen des Wachstums, des Wassergehalts, der Katalase-und Peroxydase-Aktivität sowie der Atmungsintensität festgestellt.
Die Versuche erwiesen, dass sich unter dem Einflusse einer steigenden Bestandesdichte im Zusammenhang mit dem Gesamtwachstum auch die physiologischen Vorgänge innerhalb der Pflanzen wesentlich schwächten. Diese Prozesse wurden in den Wurzeln stärker als in den oberirdischen Teilen geschwächt. Unter allen beobachteten Vorgängen wurde die Wurzelatmung am stärksten herabgesetzt. Damit hängt wahrscheinlich auch die Herabsetzung der übrigen beobachteten physiologischen Funktionen zusammen, unter anderem auch die Herabsetzung der Mineralstoffaufnahme aus dem Boden, wie in der vorhergehenden Arbeit des Autors gezeigt worden ist (1959).

The metabolism of exogenous tryptophane (3. 10^-2M) and β-indoleacetic acid (3. 10^-2M) in extirpated wheat embryos was studied chromatographically and electrophoretically.
It was established that the external application of β-indoleacetic acid in wheat embryos leads to the formation of its complex, indoleacetylaspartic acid. Chromatographical demonstration of the components of the complex was made foliowing alkaline hydrolysis.
A complex compound also arises from exogenous tryptophane, which again frees tryptophane following alkaline hydrolysis. The assumption has been put forward that this is malonyltryptophane, reported by Andreae and Good (Dannenburg andLiverman 1957). The isolated finding of a further substance may be mentioned, which possesses similar chromatographic properties to those of the indole complex-ascorbigen. For reasons so far unknown, this substance has not been isolated again in wheat plants.

Results of the action of low doses of gamma irradiation, intensity 1-80 to 0-24 r/day, are recorded in this paper. Irradiation was carried out on a gamma field with a 0-50 g. equiv. Ra Co⁶⁰ source throughout the whole vegetative cycle.Trifolium pratense var. Jičínský was chosen as the experimental material. Growth and the yield of green matter was followed both on individually bedded out plants and on sown plots. Results of the measurement and weighing of the plants were statistically evaluated by means of the t-test and analysis of variation. Small, daily radiation doses (1.80-0.30 r per day) produced a significant stimulatory effect which was evidenced in the greater height of the irradiated plants as compared with the controls and a higher yield of green matter. In conclusion the paper deals with work that has already been carried out in this field. Experiments and measurements have shown that low doses of chronic gamma radiation are capable of stimulating plant growth. This work is confirmed by result obtained by Breslavets, Berezina and Shchibrya (1956) on other material.

This paper gives a description of a two-channel photoelectric planimeter for measuring leaf areas. It is based on the absorption of rays within the range 0.6 to 1.4μ. The flux of radiation is converted to electric signals by argentum sulphide photocells. The difference in the photoelectric currents from the measuring and control channels is amplified by a sensitive and highly stable d.-c. differential amplifier and is indicated by a meter which can be calibrated direct in area units.

The paper describes a new strain of tobacco mosaic virus which has been named S-strain of TMV because of its characteristic stripe symptoms. The Al-strain of tobacco mosaic virus was used as the initial material.
In contrast to methods used hitherto the S-strain was obtained by interfering with the metabolism of the host plant by a change in the environment. (SvobodovÁ 1954, 1958). The usual hosts of tobacco mosaic virus were used, chiefly tobacco and tomato plants. These plants were cultivated under aseptic conditions on an agar medium in Erlenmeyer flasks with a reduced amount of nutrients, a shortened period of illumination and a limited air supply, so that they were stunted. Following the passage of the initial Al-strain of TMV through these dwarfed plants changes in symptoms appeared, which became apparent only after further passages through plants grown under normal conditions in a glass house in garden soil, where the virus once again had normal conditions for reproduction. Of the new symptoms obtained, only the most striking were further studied (the symptoms of S-strain). By means of alternating of the passage of the Al-strain of TMV from normal-to dwarfed-to normal plants grown under artificial nutrient conditions, i. e. a twice or thrice repeated sudden change of environment, the new strain (S-strain) was obtained five times in all and at different times of the year. From the symptomatic point of view no differences were found in the different repetitions of this change. The results were also the same for material from tomato plants and from tobacco of the Samsun variety.
The origin of the new strain was not caused only by the stuntedness of the host plants. It was also necessary to influence its metabolism by an abnormal environment (particularly insufficient air) in the Erlenmeyer flask before and after inoculation.
Following the reverse passage of the S-strain from plants grown normally in a glass house to dwarfed plants in an artificial environment no further changes occurred. Neither did the passage to ten other hosts grown normally on garden soil and in artificial nutrient produce any further change in symptoms. The S-strain has been maintained by a succession of continuous passages throughNicotiana tabacum Samsun for six years, and each year mass inoculation of a large number of plants is carried out. We therefore now consider the change to be permanent.
Indirect influencing of the virus through a change in the metabolism of the host plant sufficed for the induction of the new strain. Its symptoms appeared only after passage through normal unaffected plants, where the virus reproduction was not inhibited by the retarded growth of the host plant. There is a certain similarity in the emergence of the S-strain and the TM44-stram, obtained byPfanchuch et al., with X-ray irradiation. However, the initial material was the ordinary green strain of TMV.
The biological, chemical and other characteristics ascertained for S-strain and a comparison of these with the characteristics of the initial Al-strain and the ordinary green strain of TMV will be published later.

1. Anagallis arvensis L. (im weiterenA. a.) besitzt eine niedrige Keimfähigkeit, aber lässt sich leicht vegetativ vermehren und pfropfen. Beim Pfropfen "auf die Flasche" ist die Inkubationsdauer kurz, minimal bis 8 Tage. Die Pfropfung "übers Kreuz", das heisst das Durchziehen des abgeschnittenen kranken Stengels durch eine Längsöffnung im Stengel, der gepfropft wird, ist nur theoretisch von Bedeutung.
2. Die Blüten gesunderA. a.-Exemplare schliessen sich bei Nacht. Die fransenförmigen Blüten bleiben länger geöffnet. Blüten mit reduzierten Blütenkronen besitzen nicht abfallende, Monate lang geöffnete Kronen. Bei uns beginntA. a. in der freien Natur gegen Ende Mai zu blühen, im Glashause, sobald die Tageslänge 12^1/2 bis 13 Stunden ausmacht.
3. Der Virusspiegel ändert sich in denA. a.-Pflanzen je nach der ontogenetischen Entwicklung der Wirtspflanze im Zusammenhang mit ihrer Periodizität. Zur Reproduktion des Virus kommt es erst, wenn die Tageslänge mindestens 12 Stunden erreicht hat. Die Viren dieser Gruppe können in den Pflanzen auch latent vorhanden sein.
4. Bei Liptovský Hrádok in der Slowakei haben wir eine FormA. a. mit kleinen rostrot gefärbten Kronen gefunden. Die ersten Anzeichen einer Erkrankung vonA. a. an Vergilbung traten bei uns Ende Juni 1957 und im Jahre 1958 erst Ende Juli in Erscheinung. Die krankenA. a.-Exemplare bilden keimfähige Samen nur in den unteren Kapseln, die sich vor der Infektion entwickelt hatten. Die Virose kann in der Natur einen entscheidenden Einfluss auf die Frequenz vonA. a. haben.
A. a., Stellaria media undVeronica chamaedrys können Indikatoren der Anwesenheit von Viren und Virosen aus der Gruppe der Akarpien sein (Stolbur, Vergilbungen, purple-top und yellow-top bei Kartoffeln).Stellaria media kann als überwinternde Pflanze, die selbst Fröste (mindestens-25°C) verträgt, eine Reservoirpflanze der Viren dieser Gruppe sein.
5. Zu Prolifikationen beiA. a., kommt es von September bis November. Zuerst werden dabei auch die Blüten, später nur die Blätter gebildet.
6. Die Fransenförmigkeit der Blütenkronen beiA. a., kann eines der ersten Anzeichen von Vergilbungserkrankung sein. Es tritt bei übertragung der Hexenbesenkrankheit der Kartoffeln, der green petals der Erdbeerstauden, der Phyllodie bei Kleearten und bei Plantago major in Erscheinung, sowie auch bei Pflanzen, die an bakteriellem Braunwerden der Stengelbasis leiden, sodann auch vorübergehend als mögliche Intoxikationsfolge der fremden Unterlage nach einer Pfropfung gesunderA. a.-Exemplare auf fadenförmige Kartoffelkeime.
7. A. a.-Exemplare, die sehr schwer an Virose erkrankt sind, blühen überhaupt nicht, verzweigen sich aber stark und bilden anstelle der Blüten Blattrosetten.
Verengung, Welligwerden und Anthokyanisierung der Blätter sind nicht immer charakteristische Kennzeichen für eine Vergilbungsvirose vonA. a.
Pfropfreiser krankerA. a.-Exemplare riefen beinicotiana glutinosa wahrscheinlich infolge einer heftigen Intoxikation und eines raschen Absterbens der aufgepfropften Pflanzenteile vonA. a. keine Krankheitssymptome hervor.
Pfropfreiser krankerA. a.-Exemplare bewirkten bei jungen Sämlingen v

Die Autoren bringen eine kurze Mitteilung uber Beobachtungen der sofortigen Veränderungen in den Zellen der Epidermis von Allium cepa durch Ultraschallwirkung. Als Beobachtungsmethodik dieser Veränderungen wurde die Fluoreszenzmikroskopie mit Akridinorange-Pärbung verwendet. Es werden vier Stadien der hervorgerufenen Veränderungen unterschieden. Auf Grund dieser Beobachtungen wird angenommen, dass die quantitative Ausbeute der Energie des Ultraschalles für biologische Vorgänge verschieden sein kann, auch wenn in den sekundären Vorgängen die Ultraschallwirkung entweder zum Absterben oder Überleben der Zelle führt. Aus zytologischen Beobachtungen wird auf kolloidal-osmotische Veränderungen geschlossen.