Five species of myxobacteria have been found to fruit more or leu@ frequently on dung pellets of rabbits, hares, and roes collected in the surroundings of Karlsruhe, West-Germany. The most common species, Myxococcua fulvus, was followed by M . virescens and Chondrococcus coralloides which occurred pretty abundantly, too. Now and again fruiting bodies of Archangium gephyra and Polyangium fuscum could be observed, in the cam of P . fuacum confined to certain substrates. Other species have been rare.
Analysing the distribution of these five relatively common species from dung pellets and soils, differences in the frequency of occurrence were demonstrated when the rather complex substrate of soil is differentiated in the upper horizon of soil without roots, and the rhizosphere of flowering plants and mosses. M. fulvus, Ch. wrralloides, and A . gephyra may be regarded as to be more or less ubiquitous species. I n some cases, M . fulvus and Ch. coralloides appeared to be rhizophilic. On the other side, P . fuscum could only be observed in soils and avoided the rhizosphere. M . virescens was found only once.
Conditions for microbial life in the rhizoidosphere of bryophytes growing on rocks can be regarded in a modified sense as such in soils in the f i r s t steps of their development. Among the fruiting myxobacteria it resulted that in addition to M . fulvus, M . virescens, Ch. coralloides, and A . gephyra, Podangium lichenicolum occurred quite frequently, whereas Polyangium juscum could not be observed. I n well-developed soils, however, Podangium lichenicolum was missing, and Polyangium fuscum was found frequently. l) Die vorliegende Arbeit ist die gekiirzte Fassung einer Dissertation der Fakultiit fiir Bio-und Geowissenschaften der Universitiit (TH) Karlsruhe.