548 HILDA HEMPL HELLER 



to most laboratories is stratification with vaseline. After 

 incubation the culture should always be boiled to expel carbon 

 dioxide. 



For pure culture study the exact point of the reaction of the 

 medium at the time of inoculation is not important. It is 

 important only that the reaction should be well within the limits 

 for growth of the organism studied, and not very far from neu- 

 traUty. A reaction of pH 7.2 (neutral to litmus) has been used 

 in this laboratory for most anaerobe media. The selection of a 

 reaction point for the dividing of the two types of anaerobes is 

 more difficult. Von Hibler (1908, pp. 89, 104) used the neutral 

 point of litmus. The selection of a dividing point in meat 

 medium is frankly an arbitrary affair. I suggest pH 7.0, the 

 neutral point of hydrogen-ion concentration, for the dividing 

 line between the alkali-producing and the acid-producing 

 anaerobes. 



It is unlikely that any other division of the Clostridiaceae 

 will be made which would be placed above the division into the 

 two groups just described. But I am certain that various 

 arrangements of the genera which compose these groups will 

 in time be made. There are many anaerobes that behave quite 

 alike in one way and entirely differently in other ways. If 

 this were to be a final classification of the group, or if one wished 

 to outline a temporary classification, one would give the division 

 into putrefactive and non-proteolytic anaerobes a tribal rank. 

 But I am quite certain that the makers of future arrangements 

 will want very much to utilize tribal and subtribal ranks for 

 other purposes. I had myself thought of dividing the non- 

 proteolytic anaerobes into two tribes or subtribes on the basis 

 of presence or absence of flagella, but Dr. M. Christiansen has 

 repeatedly been unable to demonstrate flagella on his whale- 

 septicaemia bacillus .which so closely resembles the vibrion- 

 septique type of organism that they should probably be placed 

 in the same genus. But tribal and sub-tribal classifications are 

 sure to be made by someone before long and it will be a better 

 provision for the future to give the proteolytic-non-proteolytic 

 division sub-family rank. 



