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.

Chenopodium species react on infection with tobacco mosaic virus by the formation of chlorotic or necrotic lesions and later by the abscission of infected leaves. A transition of local infection into the stem has been observed exceptionally inChenopodium quinoa, C. hybridum, andC. rubrum, but no systemic infection of the leaves followed. Systemic infection was demonstrated only inC. polyspermum andC. murale. The recovery of new sprouts was demonstrated in C.murale in the late chronic phase of infection.

Im Verlaufe der Arbeit ist festgestellt worden, dass es nach einer Sprossverletzung von Holzarten in der echten Winterruhe unter günstigen Bedingungen zu einer Aufhebung der Teilungshemmung der Zellen der meristematischen Gewebe in der Nähe der Wunde kommt. Die Kambiumzellen in einer Entfernung einiger mm von der Stelle der Verletzung und die übrigen intakten Gewebe des Sprosses sowie seine Knospen verbleiben im Ruhezustand. Bei einem Veredlungsvorgang in der Ruhezeit verwachsen unter günstigen Bedingungen, insbesondere der Temperatur und Feuchtigkeit, die Veredlungskomponenten ohne dass Knospen an den Pfropfreisern oder den Unterlagen ausschlagen.
Die auf Grund dieser Unterlage ausgearbeitete Veredlungsart der Walnussbäume hat sich praktisch bewährt. Auf einem Quadratmeter Vermehrungshaus- oder Erwärmungskammerfläche erzielen bei 26°C und einer hohen relativen Luftfeuchte im Laufe von drei Wochen cca 500 Walnussveredlungen ein Verwachsen. Die Veredlungen werden im Keller oder in einem frostfreien Raume eingeschlagen und im Frühjahre ohne Schutz nicht ausgetrieben in der Baumschule aufgepflanzt. Der Prozentteil der verwachsenden veredelten Pflanzen ist hoch.

A study was made of the action of volatile substances liberated from the rhizome of couch grass on wheat seedlings. The experiments were made in a closed atmosphere in glass vessels with continual removal of expired CO₂ and the addition of O₂.
Volatile substances liberated from couch grass produced numerous morphological and physiological changes in wheat seedlings. They caused retarding of the growth of overground parts and roots, the excessive formation of root hairs, curling of the roots and bending of the coleoptiles. The respiratory rate was higher in the leaves and roots of the experimental wheat seedlings than in the controls. The changes observed were similar to those produced by hydrocarbons of the ethylene series, which are well documented in the literature.

The work ofJermoljev andBrčák (1964) showed that the sap of potato leaves contains substances inactivating X, Y and S viruses and that there was an increasing trend in the content of these substances in varieties resistant to these viruses. In further research it was found that potato tubers of varieties which are resistant and susceptible to the viruses contained the same amounts of inactivating substances. Differences in the power of inactivating the viruses evidently appeared in the leaves. Inactivating substances could be removed by boiling, they did not pass through a dialysing membrane and were adsorbed by animal charcoal. On centrifuging sap from potato leaves in a Spinco L ultracentrifuge for 60 min. at 40,000 r.p.m., the inactivating substances remained in the supernatant. When sucrose gradient centrifugation for 60 min. at 24,000 r.p.m. was employed, the inactivating substances remained in the layer of sap and 10% sucrose. Inhibition of the activity of certain enzyme groups did not affect the power of sap to inactivate X virus. Inactivating substances could be isolated chemically. The best method of isolation, however, was fractionation of sap, after ultracentrifugation, on a Sephadex G 50 column, rinsing the column with McIlvaine buffer at pH 6.5. Inactivating substances can be isolated, concentrated and preserved by lyophilization by this method. It is difficult to say precisely to what chemical group the inactivating substances belong. Some reactions indicate that they may be low molecular proteins.

In field experiments, potato varieties with different lengths of the vegetation period were compared. The methods of growth analysis were applied to the evaluation of these experiments. Some important specific features of potato growth had to be taken into account to make the application of the growth analysis successful and to enable valid and reliable results to be obtained.

Many studies have been made on ribosomes both in plant and animal material, on account of their importance in the proteosynthesis of protein. In plant material, studies have been made on the pea by Ts'o andBonner (1956), Ts'o,Bonner andVinograd (1958),Setterfield et al. (1960) andSisakyan et al. (1963). Ribosome from spinach were investigated byLyttleton (1962) andMurakami (1963) and fromClivia byMikulská et al. (1962). As part of a wider study of the mechanism of biosynthesis of nucleic acids in apple trees, we isolated ribosomes from the young green fruit and studied them by means of electron microscopy. Young apples were selected because cell division is very intense at this stage of growth of the apple.

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 effect of the individual leaf blades of spring wheat on the dry matter of stalks, chaff and grain (caryopses), of spikes and total overground part, was studied. In the experimental plants the individual leaf blades were detached according to the scheme given, at the beginning of shooting, (A), at the beginning of earing (B), and at the beginning of flowering (C). The dry matter (fresh weight) of the stalk was least decreased if either the lowest or the uppermost leaf blade was severed during the developmental phase of shooting. The dry as well as the fresh weights of chaff were least affected in those plants where the leaf blade was removed during the developmental phase of flowering. Both the dry and fresh weights of caryopses were least decreased if either the lowest or the uppermost leaf blade was removed during the developmental phase of flowering. The dry weight as well as the relative water content of chaff and ear grains were most decreased following removal of leaf blades during the developmental phase of shooting. The relative water content of chaff, grains and ears was most decreased following removal of developed leaf blades during the developmental phase of earing. It was confirmed that in addition to the photosynthetic activity of leaves the photosynthesis of other parts of the stem system (stalk internodes, ear awns etc.) participated in the production of total dry matter of experimental plants. The photosynthetic activity of leaf blades was particularly high up to the earing phase, while subsequently the photosynthesis of extrafoliar area (stalk internodes and ears) predominated. In spite of this, participation of the total leaf area is very high in the formation of grain dry matter (over 50%), as well as of the total dry matter of plant (over 80%).

Bei Erforschung des Einflusses der herabgesetzten Bodenfeuchtigkeit auf die osmotischen Verhältnisse im Zellsafte der Kartoffelpflanzen wurde die refraktometrische Methode für die Bestimmung deren osmotischen Zustandes bewertet. Es zeigte sich die Notwendigkeit eine gewisse Vorsicht bei ihrer Anwendung zu bewahren. Die Elektrolyte, die von der refraktometrischen Methode verhältnismässig weniger erfasst werden, haben ein wessentliches Übergewicht in der Bildung der osmotischen Gesamtwerte des Zellsaftes der Kartoffeln über den anderen Hauptteil, nämlich die Fehlingslösung reduzierende Substanzen. Sie haben auch oft einen entgegengesetzten Vegetationstrend gegen den molekular aufgelösten organischen Substanzen die die Fehlingslösung reduzieren. Aus diesem Grunde ändert sich die Korrelation zwischen den osmotischen Gesamtwerten und dem Brechungsindex des Saftes in einzelnen Fällen sowohl als auch während der Vegetation. Diese Verhältnisse sind auch in einzelnen Organen der Kartoffelpflanzen verschieden.
Eine bedeutende Herabsetzung der Bodenfeuchtigkeit, dauernd oder zeitlich, verursacht nur eine relativ geringe Erhöhung der osmotischen Gesamtwerte im Vergleiche mit dem Einflusse der Wetteränderungen. Von diesen Ergebnissen folgt, dass die refrektometrische Methode nicht empfindlich genug ist, um den Einfluss der Bodenfeuchtigkeit auf die osmotischen Verhältnisse in der Kartoffelpflanze bestimmen zu können.

In this paper the values of photosynthetic intensities of spring barley leaves measured by two different methods were compared:
1. By the gravimetric method of Bartoš, Kubín and Šetlík (1960), modified by Nátr and Špidla (1961) for cereal leaves. Segments were laid on a special support and illuminated for several hours from a constant source of light. The tissues were completely saturated with water, the temperature and the flow-rate of the air were also constant. Photosynthetic intensity is expressed as the increase of dry matter in segments in mg per dm² of a double area of leaf, and per hour. The weight increase of the dry matter is converted to values corresponding to CO₂ consumption by means of a coefficient: 0.64 mg of dry matter correspond to 1 mg of CO₂, or, 1 mg of dry matter corresponds to 1.56 mg of CO₂.
2. By the gazometric method of measurement of CO₂ consumption, expressed in mg per dm² of double area of leaf, and per hour. For these measurements an infrared analyser was used under the following conditions: open system, constant illumination, temperature (25°C) and air humidity (45%), as well as constant CO₂ content in the air (0.033 vol.%).
The results prove that in most instances both methods afford, from the quantitative point of view, completely corresponding results. As a cause of a few discrepancies met in some experiments, the influence of cutting off of the leaves and uneasily seizable differences in experimental conditions during the exposure of leaves and segments can be considered. Further, the calculated value for the conversion coefficient, i.e. 0.64, must not in every case necessarily correspond to the chemical composition of formed assimilates. The existence of inhibitory influence of accumulated assimilates in leaf segments on the photosynthetic intensity can be excluded.
When the CO₂ consumption of cut off and non-cut leaves of the same experimental plant was measured, no differences could be observed.
The advantages and possibilities of the use of dry matter increment determination in segments as a measure of photosynthetic intensity are discussed.

Es wird auf Grund von Untersuchungen der chloralysierten Wurzeln vonVicia faba das gegenseitige Verhalten von diploiden und polyploiden Zellen und Geweben diskutiert und konkrete Beispiele angeführt. In ganz jungen Wurzeln entwickeln sich die mixoploiden Gewebe friedlich neben einander, wachsen, teilen und differenzieren sich normal. Aber später, besonders wenn die Wurzelspitzen hoch polyploide Gewebe (8 n, 16 n) enthalten, verhalten sich dieselben gegeneinander feindlich. Die polyploiden Sektoren werden abgetrennt und stellen Teilungen ihrer Zellen sowie ihr Streckungswachstum frühzeitig ein. Es kommt zu Gewebespannungen und in den polyploiden Sektoren kommt es zuweilen zur Bildung von rhexigenen Höhlungen. Diese Vorgänge werden schon im Urmeristem vorbereitet und es kommt zur Unterbrechung der normalen Korrelation zwischen den Geweben verschiedener Ploidie. Zur Homoploidisierung kann auch die Reduktion der Chromosomenzahl in polyploiden Zellen beitragen. Die verschieden hoch ploiden Gewebe können von einander durch Metakutisierung oder Verschleimung der sie trennenden Zellwände getrennt werden. Es handelt sich um verschiedene Vorgänge von Autoregulation, welche zur Diploidisierung, seltener zur völligen Polyploidisierung führt. Die Spitzen älterer mixoploider Wurzeln werden auf diese Weise homoploid.

For specific staining of TMV inclusions the cytochemical method of Hršel for the determination of tryptophan containing proteins was used. This method makes it possible to obtain series of sections in contrast to the methods employed up to the present, so that TMV inclusions from any part of the plant can be detected. Staining was tested "in situ" as well as in preparations of isolated virus particles.

1. Teucrium Scorodonia L., plante vivace et caulescente, doit être placèe à 3°C pendant 8 semaines au moins, pour être vernalisé.
L'induction et l'initiation florales ont lieu en jours longs.
2. Chez cette plante, l'état vernalisé est instable dans les bourgeons axillaires ainsi que dans le bourgeon terminal qui peut être dévernalisé, même après une réfrigération complètement vernalisante, par des photopériodes courtes ou par des températures élevées (35°C).
D'autre part, la dévernalisation des bourgeons axillaires consécutive à l'inhibition de la croissance de ces bourgeons par la dominance apicale, est un mécanisme naturel assurant la pérennité de la plante.

After the decapitation and amputation of one cotyledon in germinating pea seedlings, the axillary bud of the amputated cotyledon always grows and the growth of the axillary bud of the remaining cotyledon is inhibited. Before morphological differences appear between the axillary bud of the amputated and preserved cotyledon, a higher endogenous gibberellin content can be demonstrated chromatographically in the axillary bud of the amputated cotyledon. This indicates that the increased growth of the axillary bud of the amputated cotyledon is in connection with an earlier increase in the activation of endogenous gibberellins.

Using the time-lapse cinematography technique, activity of the growing centres of the pea seed hypocotyl (Pisum sativum L.) was followed in the course of the early phases between 15 and 60 hours of germination under standard experimental conditions. The resulting data were plotted in a summary graph with conjugates scales (Fig. 4) indicating time-space limits for further biochemical analysis and the interpretation of mechanism of hypocotyl elongation concerning the dependence of the IAA and RNA content, growth rate, localization of growing zones, transport of substances from the swollen cotyledons into the embryo etc. The most important results are as follows: Between 15 and 20 hours of seed swelling, activity is manifested in two growing centres of the hypocotyl (Fig. 5); between 30 and 36 hours only one zone becomes localized, with a maximum elongation in the region which was originally at a distance of 2.5 mm. from the hypocotyl base. The greatest elongation of the hypocotyl-0.77 mm./hour- was observed between 30 and 48 hours in the zone which was originally at a distance of 2.75 mm. from the hypocotyl base. The zone of maximum growth did not become localized by the termination of the experiment (60 hours) in the presumed zone close to the apex, but was displaced further to the zone which was originally at a distance of 4.0 mm. from the hypocotyl base.

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.

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.

When the epicotyl and one cotyledon is cut off from pea seedlings, only the axillary of the amputated cotyledon is known to grow. When³²P is applied to the roots of such plants, then a higher radioactivity appears in the axillary of the amputated cotyledon already 24 hrs. after amputation of one cotyledon, although this axillary is of the same size at this time as that of the remaining cotyledon. This fact indicates a more extensive material transport to the axillary bud of the amputated cotyledon already during the first day after amputation
The effect of individual regulators on the³²P transport was investigated in an experiment where pea seedlings cultivated in the dark were decapitated and a 0.5% paste, containing the regulatory compounds was placed either on the cutting surface in the apical part of the epicotyl stump or in its central part. After a week the plant roots were supplied with³²P and its transport to the upper part of the epicotyl stump was followed. This transport increased about 10-fold in the case of a paste, containing indolyl acetic acid, when the paste was spread on the apical cutting surface of the stump. However, the transport was inhibited when the paste was applied in the central part of the stump. These results indicate that only the transport of³²P towards the paste with indolyl acetic acid is accelerated, whereas it is decelerated above this paste. A paste, containing triodobenzoic acid inhibited³²P transport only when applied to the apical cutting surface of the epicotyl stump and not when spread over the middle part. In this case³²P transport was more rapid above the paste than towards the paste. The situation was similar in the case of gibberellin and kinetin.

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.