i8 



THE STORY OF GERM LIFE. 



vary all the way from a length scarcely longer 

 than their diameter to long threads. About the 

 same may be said of the spi- 

 ral forms. They are decid- 

 edly the smallest living or- 

 ganisms which our micro- 

 scopes have revealed. 



In their method of growth 

 we find one of the most char- 

 acteristic features. They 

 universally have the power 

 of multiplication by simple 

 division or fission. Each in- 

 dividual elongates and then 

 divides in the middle into 

 two similar halves, each of 

 of bacteria : a, Spheri- which then repeats the pro- 

 cal forms ; b, Rod- ces s. This method of mul- 

 tiplication by simple division 

 is the distinguishing mark 

 which separates the bacteria from the yeasts, the 

 latter plants multiplying by a process known as 

 budding. Fig. 2 shows these two methods of 

 multiplication. 



While all bacteria thus multiply by division 

 certain differences in the details produce rather 

 striking differences in the results. Considering 

 first the spherical forms, we find that some species 

 divide, as described, into two, which separate at 

 once, and each of which in turn divides in the op- 

 posite direction, called Micrococcus, (Fig. 3). Other 

 species divide only in one direction. Frequently 

 they do not separate after dividing, but remain 

 attached. Each, however, again elongates and di- 

 vides again, but all still remain attached. There 

 are thus formed long chains of spheres like strings 



FIG. i. General shapes 



shaped forms ; c, Spi- 

 ral forms. 



