124 BACTERIA, YEASTS, AND MOLDS 



One of the rod-shaped forms lengthens itself and divides 



in the middle and produces two individuals, each of which 



again lengthens and divides (Fig. 52, c, d). The same method 



is found in the spiral bacteria. This manner of division, 



which is characteristic of all bacteria, will be seen to be 



quite different from the method we have already noticed 



in the yeasts. Indeed, the distinction between yeasts and 



bacteria is based upon this method of multiplication. The 



^ -^ ^.^ ^ method of multi- 



, ^^^^ ^^ plication in bac- 



bOOOO CXXDO OOOOCO CXDOOCXDCO f • • , 



teria is known as 



c CD CZD CXD □□ cmCD fission, and this 



</0 CID c::CD CDO ^<^ rP group of fungi are 



_, _^ ^T-, ,r-iroCf-' f) called fission fungi 



e A^ in distinction 



CD 0=3 Oa mr-T-. CH^O'^ f''°™ ^he yeasts, 



_, 01. • .u .1. J ..,•,■ ■ which are called 



Fig. 52. Showing the method of multiplication 



by fission, a, a coccus form ; b, a strepto- budding fungi. The 

 coccus ; c and d, short rods ; e, showing sue- difference between 

 cessive stages in the formation of chains, ^^ese twO classes 

 arising by fission from single cells. 



can be distin- 

 guished only by careful microscopic study, but it is the 

 scientific distinction between the two groups. 



Spore Formation. Under some circumstances bacteria 

 have a different method of reproduction. Inside of the 

 body of a single individual bacterium appears a little 

 rounded mass which is known as a spore (Fig. 53). This 

 spore may be broader than the rod which produced it, 

 or it may be narrower ; but it finally breaks out, the 

 bacterium itself disappearing and the spore then coming 

 out freely in the medium in which it lives. These 



