116 UNIVERSITY OF WISCONSIN STUDIES 
here in the United States. No one, so far as I know, has at- 
tempted to differentiate them on clinical grounds. 
Therapeutically they responded promptly to potassium 
iodide as did the later French and American cases. 
The morbid anatomy and histology in the human were, so 
far as studied, the same in the two types, the Jesions being 
those of a chronic abscess. In experimental atimals the 
lesions produced by the two types are identical as admitted by 
Gougerot. 
Bacteriologically there is greater opportunity to detect 
minute or subtle differences should they be present and these 
we shall consider in detail. In the cases of Schenck and of 
Hektoen and Perkins, the organisms were not seen in the 
human tissues or in the pus. In experimental animals the 
organisms appeared as oval and elongated forms with ocea- 
sional round forms. They stained with Gram. In no way 
did they differ from the forms seen in tissues infected with 
organisms of the French strains. I have made a special 
study?° of the tissue forms in experimental animals using 
strains from France and from America as well as the Schenck- 
Hektoen strain. No differences could be detected between 
them. When these various strains are grown in animal fluids, 
blood ete., in the test tube, elongated forms similar to those 
seen in the tissues are produced and here again no differences 
between the various strains were noted. 
The question of the virulence of the various strains may 
not be of any importance in differentiation since this property 
is such a variable one. However, it may be stated that the 
Schenck-Hcktoen strain even after years of artificial culture 
is still about as virulent for rats as are the freshly isolated 
strains of the French type. According to the paper of 
Schenck, these organisms were virulent for mice and dogs. 
Hektoen and Perkins produced lesions in mice, dogs, rats and 
guinea pigs (slight). As far as these results are comparable 
with those obtained with the French and later American 
strains, they agree in all essential points. 
We now come to a discussion of the morphological and 
cultural characteristics, both microscopic and macroscopic, of 
“ Davis, Jour. Infect. Diseases, 12, p. 458, 19138. 
