Generic Characters in the Coccaceae 



171 



method suggested by Clark and Gage (1905), which consists in inocu- 

 lating gelatin tubes of 10 mm. diameter by spreading a suspension 

 of the culture over the surface. Liquefaction proceeds in a strati- 

 form fashion, and its amount may be read off in centimeters. With 

 such a method one may determine the rapidity of hquefaction either 



80 

 70 

 60 

 50 

 40 

 50 

 20 

 10 



. 



.55 .85 1.55 1.85 2.55 2.85 5.55 585 



Fig. 4. — Liquefaction of gelatin by 314 cocci. Abscissae, liquefaction in cm. Ordinatcs, number 

 of cultures. 



by the number of days required to reach a fixed point, or the final 

 amount of liquefaction. In general, these two values are pretty 

 closely correlated, but in a preliminar)^ study we found that the 

 final differences are somewhat sharper as well as easier to record. 

 We have therefore adopted as (jur routine measure of liquefying 

 power the depth of liquefaction after 30 days. 



