BACTERIA 97 



structure which is changed in appearance; the cytoplasm vacuolizes and 

 ends by displaying a fine alveolar structure. The web contains in its 

 knots small, highly stainable granules (Fig. 75, 2 and 3). In some 

 cases (cultures on special media for example), there is noticeable a 

 localization of these granules at the center of each cell, forming a 

 granular region which recalls somewhat the appearance of a large 

 nucleus and which is separated into two portions at the time of the 

 cellular division as if it were indeed a true nucleus (Fig. 75, 7 and 10). 



These granules fix the nuclear stains, and it seems permissible to 

 consider them chromatic in nature. 



At the time of sporulation there forms at one of the poles of the 

 cell a small oval mass, easily stained, which is like a nucleus in appear- 

 ance (Fig. 75, 4 and 5). This results from the condensation of part of 

 the chromatic granules of the cytoplasm, gradually grows larger, and 

 changes to a spore. When the spore has reached a certain size, it is 

 surrounded by a membrane which prevents the penetration of ordinary 

 stains (Fig. 75, 6); it appears then like a large colorless sphere in the 

 stained cytoplasm of the cell (Fig. 75, 6). 



At no stage of the development have we observed the least trace of 

 a nucleus. May there be a nucleus which our present technic would 

 not enable us to differentiate? That has seemed to us scarcely probable, 

 for if this nucleus existed, it would certainly be visible in a species 

 as large as B. biitschlii and would not have escaped Schaudinn. The 

 most reasonable hypothesis, the one which we have adopted, is to 

 consider like Schaudinn that bacteria contain chromatin more or less 

 mingled with cytoplasm, differentiated in the case of small grains and 

 condensing at the time of sporulation to form the spore which would 

 consist principally of chromatin. The cells of bacteria would accordingly 

 have a very primitive structure. 



Granted the clearly demonstrated existence of this particular struc- 

 ture in the Cyanophyceas, there is no reason for not admitting that the 

 nucleus, very rudimentary in the Cyanophycece, might be even more so 

 in bacteria, being reduced to a diffuse nucleus consisting of chromatic 

 grains scattered in the cytoplasm. 



These observations have, moreover, received a series of new con- 

 firmations by the labors of a great many authors (Swellengrebel, 

 Ruzicka, Ambrez, etc.) and especially by the later researches of Dobell. 

 The latter investigator discovered, in the intestines of frogs and toads, 



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