SEXUALITY IN BACTERIA IO3 



details ot the sexual fusion which presumably preceded this process were not 

 recorded, but the remarkable cross-like figures of the meiotic division are 

 clearly illustrated in photomicrographs. It is unfortunate that the " vital " 

 staining technique used in this study was capable of demonstrating these 

 structures, but not the rest of the cytological processes which must 

 undoubtedly have occurred in the same organism. 



C: SYNGAMOUS VEGETATIVE REPRODUCTION 



(6, 7, 14, 25) 



In this section and the next the sexual processes of eubacteria and myxo- 

 bacteria will be discussed together. The cytology of myxobacteria was 

 known long before that of eubacteria, but the two are entirely similar in so 

 far as the behaviour of the nucleus is concerned. The vegetative cells, which 

 have already been discussed, may undergo what appears to be an autogamous 

 process, in the course of a method of reproduction alternative to simple 

 fission (Chapters IV and V). The mode of formation of the chromosome 

 fusion nucleus, with its characteristic arrangement of three pairs of chromo- 

 some complexes, in the smooth type of: bacterium, is obscure, and to refer 

 the problem to the supposed precursor cells, with their three pairs of complexes, 

 arranged in a more usual manner, does Uttle to elucidate the problem. It is, 

 however, almost certain that the trinucleate precursor cell does, in fact precede 

 and not follow the fusion cell, because the latter appears invariably to undergo 

 at least one nuclear division while the chromosome complexes are still packed 

 closely together. The entire mechanism may be equivalent to the formation 

 and dispersal of a symplasm, with the exchange of nuclear material ; a method 

 of reproduction which is common in both fungi and protozoa. The symplasm 

 is represented by the filamentous cell, which although far from formless, is 

 an aggregate containing the nuclear material of several cells, into which it 

 subsequently divides. The bacterial cell has so marked a tendency to adopt 

 a filamentous form of growth that a comparatively disorganised filament of 

 this kind may reasonably be compared to a symplasm in cells of less regular 

 outline. 



