540 HILDA HEMPL HELLER 



of making such collections and of keeping close watch on all 

 strains to insure their purity is tremendous. The bacteriologist 

 is not the only systematist who has to do with such a problem 

 as ours. The classifier of the Coccaceae is in the position of the 

 curator of a museum who has before him the skins of a hundred 

 or two of squirrels or other rodents, their measurements and 

 habitat given, their skulls freed of muscle reposing in tiny bottles 

 by their sides. The classifier of the anaerobes is today in the 

 position of the exploring zoologist who sets his traps at night 

 on his journey and catches one or two or three new rats or mice 

 that do not resemble any thus far met by him. Both men 

 describe new species and both serve science in so doing. But 

 the museum worker may use as his type-species the animal whose 

 characters are an average of those of all the rest, while the 

 exploring zoologist must call the ''type" one of his chance catches 

 which may be a freak in one or more ways. And yet we would 

 not have the explorer place his mice from a far country nameless 

 in a museum for a future zoologist to describe some seventy- 

 five years hence when the far country has been settled and the 

 mice have been caught by the hundred. 



The problems presented in the classification of the Coccaceae 

 and of the Clostridiaceae are quite different in other ways. The 

 anaerobes form a group of far more diverse types of organisms, 

 both from the morphological and from the physiological stand- 

 point, than do the cocci. One may say that their characters are 

 more salient, more easily perceived, or more definite in their 

 nature, than are those of the cocci. Or one may state with 

 equal truth that the anaerobic group is a less homogeneous one 

 than that of the cocci. One would also be justified in stating 

 that the anaerobic species and genera are far more numerous 

 than are those of the Coccaceae. Therefore a representative 

 and adequate collection of anaerobic strains for statistical study 

 would have to contain not hundreds but thousands of strains. 

 But this element of distinctive characters places in our hands 

 a means for the determination of genera before we are familiar 

 with many strains of each genus. 



