THE STRUCTURE OF BACTERIA. 33 



are sketched out in their final size and shape 

 and do not, as in the first type, gradually in- 

 crease their substance at the expense of the 

 rest of the protoplasm. During the process of 

 maturation, the nutrition of the spore-rudiment 

 is provided for by the rest of the cell-proto- 

 plasm, and, as the cilia bear witness, the move- 

 ments of these species do not cease during 

 spore-formation. Endospores are most com- 

 mon among the rod-bacteria, but they have also 

 been positively observed in coccus and spiral 

 forms. 



Pasteur succeeded in suppressing spore-for- 

 mation in the anthrax bacillus by subject- 

 ing it to a temperature of between 42 and 

 43. Roux 1 and Phisalix 2 obtained a similar 

 result by the addition of carbolic acid to the 

 culture medium, a simultaneous weakening of 

 the physiological activities of the germ occur- 

 ring in both cases. The hereditary repression 

 of such an important morphological character- 

 istic as spore-formation was, however, not 

 effected. 



A mode of spore-formation similar to that 

 of bacteria has as yet been observed only 

 among some monads and flagellates as in 

 the so-called cyst-formation, for example, in 



1 Ann. de 1'Inst. Pasteur, 1890, p. 24. 



2 Le Bull, med., 1892, No. 35; La Semaine m<*d., 1892, No. 40. 



3 



