COMPARATIVE STUDY OF THE COCCI 7 1 



fying form and the other with almost no peptonizing 

 power, Smith (1900) records a similar experience with 

 colon-bacilli and forms of B. proteus. 



In studying liquefaction we determined only the extent 

 of the action exerted. The shape of the liquefaction 

 in the stab culture has been shown by Whipple (1902) 

 to vary within the widest limits, with slight differ- 

 ences in the character of the medium; and the Com- 

 mittee on Standard Methods (1905) has omitted this 

 character from its list. 



For determining the amount of liquefaction we used 

 the method suggested by Clark and Gage (1905), which 

 consists in inoculating gelatin tubes of 10 millimeters 

 diameter, by spreading a suspension of the organism over 

 the surface. Liquefaction proceeds in a stratiform fashion, 

 and its amount may be read off in centimeters. With 

 such a method one may determine the rapidity of lique- 

 faction either by the number of days required to reach 

 a fixed point or by the final amount of liquefaction. In 

 general, these two values are pretty closely correlated, 

 but in a preliminary study we found that the final differ- 

 ences after a fixed period were somewhat sharper as well 

 as easier to record. We therefore adopted the depth of 

 liquefaction after 30 days as our routine measure of 

 liquefying power. 



Supplementary tests. Many other tests than those 

 mentioned are sometimes used in bacterial diagnosis, 

 but none of them seemed suited to the present investi- 



