GENERAL CHARACTERISTICS OF BACTERIA. 49 



the interior of a cell very much enlarged in its central 

 portion, giving it a spindle shape. 



The germination of spores takes place as follows : 

 By the absorption of water they become swollen and 

 pale in color, losing their shining, refractile appear- 

 ance. Later a little protuberance is seen upon one side 

 or at one extremity of the spore, and this rapidly 

 grows out to form a rod which consists of soft-growing 

 protoplasm enveloped in a membrane which is formed 

 of the endosporium or inner layer of the cellular en- 

 velope of the spore The outer envelope, or exosporium, 

 is cast off, and may be seen in the vicinity of the 

 newly-formed rod. Sometimes the vegetative cell 

 emerges from one extremity of the oval spore, and 

 in other species the exosporium is ruptured and the 

 bacillus emerges from the side. 



In old cultures of bacteria, where the deleterious sub- 

 stances have developed and the food-stuffs have been 

 largely used, there are frequently found very irregular 

 or distorted forms, due to the abnormal development and 

 division of the bacterial cells under the unfavorable 

 conditions present. These are spoken of as involution 

 or degenerated forms. If these deformed cells are placed 

 under suitable conditions they produce again normally 

 fashioned organisms. 



