58 BACTERIOLOGY. 



ends of the young cells are flattened, while the distal 

 extremities may be rounded or slightly pointed (Fig. 

 3, e). The segmentation of the anthrax bacillus, with 

 which we are to become acquainted later, results, when 

 completed, in an indentation of the adjacent extrem- 

 ities of the young segments, so that by the aid of 

 high magnifying powers these surfaces are seen to be 

 actually concave. Bacilli never divide longitudinally. 



SPORE-FOKMATION. With the spore-forming bacilli, 

 under favorable conditions of nutrition and temperature, 

 the same mode of segmentation is seen to occur during 

 vegetation ; but as soon as these conditions become 

 altered by the exhaustion of nourishment, the presence 

 of detrimental substances, unfavorable temperatures, etc., 

 they enter, in their life-cycle, the stage to which we 

 have referred as spore-formation. This is the process 

 by which the organisms are enabled to enter a state in 

 which they resist deleterious influences to a much higher 

 degree than is possible for them when in the growing or 

 vegetative condition. 



In the spore, resting, or permanent state, as it is vari- 

 ously called, no evidence of life whatever is given by the 

 spores ; though as soon as the conditions which favor 

 their germination have been renewed these spores de- 

 velop again into the same kind of cells as those from 

 which they originated, and the appearances observed in 

 the vegetative or growing stage of their history are 

 repeated. 



Multiplication of spores, as such, does not occur ; they 

 possess only the power of developing into individual 

 rods of the same nature as those from which they were 

 formed, but not of giving rise to a direct reproduction oj 

 spores. 



When the conditions which favor spore-formation 



