34 



PRINCIPLES OF BACTERIOLOGY 



The germination of spores (Fig. 19) takes place as follows: By the 

 absorption of water they become swollen and pale in color, losing their 

 shining, refractile appearance. Later, a little protuberance is seen upon 

 one side or at one extremity of the spore, and this rapidly grows out to 



FIG. 19 



FIG. 20 



123 



Showing methods of spore germination : .1, polar germination of B. butyricus (after Prazmowski); 

 B, equatorial germination of B. subtilis (after Prazmowski); C-D, equatorial germination of B. 

 tumescens and of Bact. carotorum (after A. Koch); E-F, polar germination of Bact. sessile (after 

 L. Klein); H, germination by absorption of B. anthracis (after De Bary); G, endogermination in 

 spirillum endoparagogicum (after Sorokin); 1-K, spore formation in Bact. anthracis (after Migula). 



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 envelope 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. 



INVOLUTION FORMS. In old cultures of 

 bacteria, in old abscesses, and in other 

 places where the deleterious substances 

 have developed and the foodstuffs have 

 been largely used, the rapidity of division 

 of the bacteria is lessened and 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 pro- 

 duce again normally fashioned organisms. Cocci may produce irregular 

 rods and bacilli threads. In old abscesses the involution forms may 

 look entirely different from the well-developed cells. 



METACHROMATIC GRANULES. These appear in unstained bacteria 

 as light-refracting, in stained preparations as deeply stained, granules. 



Involution forms from bacilli. 

 (From Fliigge.) 



