REPRODUCTION 25 



considerably. Perhaps a proper conception of some organ- 

 isms can be obtained when one considers that to cover one 

 square inch in single layer it would require 6,250,000,000 

 influenza bacilli, a very small organism, or 45,000,000 anthrax 

 bacilli, a bacterium of moderate size. Bacteria are measured 

 in terms of microns. The metric unit, a micron, equals 

 about 2TtfFo of an inch. 



-w 



v-<>$ 



o-r % 



d e f 



FIG. 3. a, bacilli in pairs; 6, single bacilli: c and d, bacilli in threads; e and /, 

 bacilli of variable morphology. (Abbott.) 



M 

 6 c d 



FIG. 4. a and d, spirilla in short segments and longer threads the 

 so-called comma forms and spirals; 6, the forms known as spirochetfe; 

 c, the thick spirals sometimes known as vibrios. (Abbott.) 



REPRODUCTION. 



Bacteria multiply by a simple dividing of their proto- 

 plasm. The spherical organisms divide much as one cuts 

 an apple through the poles, the divided halves rapidly 

 assuming the shape of the mother cell. The rods and spirals 

 divide by simple transverse pinching in at about the middle 

 of their long axis. 



