Morphological Studies in the Life-Histories of Bacteria. 47 5 



At the outset of the work, considerable difficulty was encountered in 

 making satisfactory morphological studies of the organisms in question, on 

 account of their small size, ordinary cultures of members of the enteric 

 group providing organisms varying in size from appro xim ately 0*5 to 2 fi. 

 In Benians' Congo-red adsorption method, described by him in 1916 (4), I 

 found, however, an invaluable method for studying the morphology of 

 killed organisms, without any of the disadvantages inseparable from the 

 use of basic stains, though in all cases the results obtained by the 



Equal Binary Fission. 

 A B 



Fig. 4. — B. Y of Hiss. Acid broth + 20 to phen. mixed with broth sub-culture from same. 



Congo-red method were confirmed by staining methods as well. The 

 chief advantage of the method is the apparent increase in size of bacteria 

 when emulsified with Congo red, as compared with the results obtained by 

 staining methods, or even by Bum's adsorption method. 



This apparent increase in size, however, was not sufficient for my purpose, 

 as, although evidence of complex life-histories can — once one's attention has 

 been arrested thereby — be unmistakably made out, both in stained films and in 

 Congo-red films of ordinary cultures in + 10 broth, the size of the organisms 



VOL. LXXX1X. — B. 2 R 



