32 THE FUNDAMENTAL PRINCIPLES. 



FIG. 4. 



a. Bacilli in pairs. 5. Single bacilli, c and d. Bacilli in threads, e and /. 

 Bacilli of variable morphology. (Abbott.) 



FIG. 



a and'rf. Spirilla in short segments and longer threads the so-called comma 

 forms and spirals. &. The forms known as spirochaeta. c. The thick spirals some- 

 times known as vibrios. (Abbott.) 



FIG. 



"'if 



a. Spirillum of Asiatic cholera (comma bacillus) ; normal appearance in fresh cult- 

 ures, b. Involution-forms of this organism as seen in old cultures. (Abbott.) 



recognized as those belonging to the original bacteria. These 

 points are shown by Figs. 2, 3, 4, 5, 6. 



