92 MORPHOLOGY AND CTJLTUEE OF MICROORGANISMS 



of a thin cytoplasmic layer, less easily stainable, surrounding the 

 central body. Biitschli compares this structure with the one which 

 has been demonstrated in the Cyanophycea, and claims that the central 

 body represents the equivalent of a nucleus. It would be a sort of large 

 nucleus occupying most of the cell, not bounded by a membrane, and 

 scarcely distinct from the cytoplasm. This structure has recently been 

 verified in Chromatium okenii by Dangeard. The Sulpho-hacteria, 

 however, are organisms morphologically entirely distinct from ordinary 

 bacteria, and are apparently directly related to the Cyanophycea. 

 Such a structure is not found in other bacteria, in which it is impossible 

 to demonstrate a central body and in which, one must adinit, the 

 nucleus is still more diffuse. 



To Schaudinn we are indebted for the most exact observations in 

 favor of the theory of the diffuse nucleus. He had the good fortune 

 to discover in the intestine of the cockroach, Periplaneta orientalis, a 

 bacillus of very large size which he named B. bUtschlii. It is the largest 

 baciUus known at present {^y. wide), and lends itself readily, therefore, 

 to cytological studies. His minute observations have shown that 

 there is no nucleus. The cells enclosing a finely alveolar cytoplasm, 

 whose net contains many small grains which take nuclear stains 

 (Fig. 71, 1-6). 



At the time of sporulation the chromatic grains increase in size 

 (Fig. 71, 7-9), then gather at the -center of the cell in a kind of axial 

 wreath (Fig. 71, 10). The two extremities of this wreath quickly swell 

 with an accumulation of chromatic grains and form two granular 

 masses, one at either pole. These two masses form the beginning of 

 the two spores, for each-cell forms two spores (Fig. 71, 11 and 12). 

 The grains which^compose these two rudiments then condense to form 

 two large homogeneous granules (Fig. 71, 13) which strongly resemble 

 nuclei and which Schaudinn considers to be such. Around these two 

 granules is soon condensed a thin cytoplasmic zone which in turn is 

 separated from the surrounding cytoplasm by a membrane (Fig. 71, 

 13). Henceforth the spores cannot be stained by ordinary means 

 because of the thickness of their membrane which prevents the pene- 

 tration of stains (Fig. 71, 14). The granules of the wreath, which 

 joined the two rudiments of spores, gradually disappeared as well as 

 the cytoplasm, while the spores increased in size. Then the sporangium 

 ended by breaking and setting free the two spores. Germination con- 



