SPOEE-FORMATION. 35 



easily differentiated from the remainder of the cell, 

 which now consists only of a cell-membrane and a per- 

 fectly transparent, clear fluid which surrounds the spore. 

 Eventually both the cell-membrane and its fluid con- 

 tents disappear, leaving the oval spore free in the medium 

 in which it has been formed. 



The spore, when perfectly developed, is highly glis- 

 tening, oval in contour, and has the appearance of being 

 surrounded by a dark, sharply defined border. It pos- 

 sesses no motion other than the mechanical tremor com- 

 mon to all insoluble microscopic particles suspended in 

 fluids, and it remains quiescent until conditions favor- 

 able to its subsequent development into the vegetative 

 form from which it originated, appear. Occasionally 

 the membrane of the vegetative cell in which the spore 

 is formed does not disappear from around it, and the 

 spore may then be seen lying in a very delicate tubular 

 envelope. Now and then remnants of the envelope may 

 be noticed adhering to the spore which has not yet be- 

 come completely free. 



When stained, the spore-containing cells do not take 

 up the dyes in a homogeneous way. By the ordinary 

 methods the spores do not stain, so that they appear in 

 the stained cells as pale, transparent, oval bodies, sur- 

 rounded by the remainder of the cell, which has taken 

 up the staining. 



A single cell produces but one spore. This may be 

 located either at an extremity or in the centre of the 

 cell. 



Occasionally spore-formation is accompanied by an 

 enlargement of the cell at the point at which the process 

 is in progress. As a result, the outline of the cell loses 

 its regular rod shape and becomes that of a club, a 



