GENERAL MORPHOLOGICAL CHARACTERS. 157 



of aberrant forms which are due to their involution and 

 decay; flask-like swellings may be associated with 

 stunted, shrunken, and broken up forms. 



It is a characteristic of many 

 fission fungi that they only occur 

 under one form of growth, e.g., only 

 in the form of micrococci. Other 

 varieties of fission fungi present 

 various forms of growth through Fi s- 32. Involution 



... i T -I i forms. 



which each individual passes in a 

 definite order during its development; thus many bacilli 

 grow to threads ; in the threads spores are formed, and 

 from the spores bacilli are again developed. The bacillar 

 thread and spore forms belong therefore to the cycle of 

 development of this bacterium. 



Besides the general characters of the vegetative forms 

 which have been described, some slighter morphological 

 differences characteristic of the one or other species 

 can be made out in spite of the small dimensions of the 

 fission fungi. Either it is the size of the individuals Morphological 



,.,.,.. ,, . , differences in 



which is ol importance, the one form growing only as the same 

 very large cocci (megacoccus) , which have a diameter f 3 | m tatlve 



Fig. 33A. Morphologically Fig. 33s. Morphologically 



different cocci X 700. different bacilli X 700. 



of 1J to 2 ft or more ; other kinds forming very small 

 micrococci 0*1 to 0*2 //. in diameter, &c. Still more Morpholog-i- 

 manifold and typical differences are found among the specie" 

 bacilli; those of one species may be lank and thin, 

 those of another short and thick ; the one very large, 

 the other extremely fine and delicate ; or the one may 

 have the ends rounded off or almost pointed, while the 

 other are sharply truncated or even somewhat concave. 



Individual differences in form may also occur in one Individual 

 and the same species of bacterium. In this respect the tia^ame^ 

 age of the individual is of the greatest influence ; young 8 P ecies - 

 bacilli appear shorter than older forms ; cocci just 

 formed by fission are often smaller tb^n those which 



