Reproduction 33 



ideally favorable, form a mass which can scarcely be reck- 

 oned in numbers." "Fortunately for us," says Woodhead, 

 "they can seldom get food enough to carry on this appalling 

 rate of development, and a great number die both for want 

 of food and because of the presence of other conditions 

 unfavorable to their existence." 



Sporulation. When the conditions for rapid multiplica- 

 tion by fission are no longer good, many of the organisms 

 guard against extinction by developing small eggs, seeds, 

 or, as they are correctly called,, spores (Fig. i). 



Endospores. Spores developed within the bacteria are 

 called endospores. 



Endospores are generally formed in the elongate bacteria, 

 bacillus and spirillum, but Zopf has observed similar 

 bodies in micrococci. Escherich also claims to have found 

 undoubted spores in a sarcina. 



Spores may be either round or oval. As a rule, each 



a b c d e f 



dD cz :^) (o) o o 



Fig. 1. Diagram illustrating Sporulation: a, Bacillus inclosing a 

 small oval spore; b, drumstick bacillus, with the spore at the end; c, 

 clostridium; d, free spores; e and /, bacilli escaping from spores. 



organism produces a single spore, which is situated either 

 at its center or at its end. When, as sometimes happens, 

 the diameter of the spore is greater than that of the 

 bacillus, it causes a peculiar barrel shape bulging of the 

 organism, described as clostridium. When the distending 

 spore is at the end, a "Trommelschlager," or "drum- 

 stick," is formed. End-spores are almost characteristic 

 of anaerobic bacilli. When the formation of a spore is 

 about to commence, a small bright point appears in the 

 cytoplasm, and increases in size until its diameter is nearly 

 or quite as great as that of the bacterium. A dark, highly 

 refracting capsule is finally formed about it. As soon as 

 the spore arrives at perfection the bacterium seems to die, 

 as if its vitality were exhausted in the development of the 

 permanent form. As the degeneration of the cytoplasm 

 sets the spore free, it appears as a clear, highly refracting 

 sphere or ovoid. 



The spores differ from the bacteria in that their capsules 

 3 



