128 UNIVERSITY OF WISCONSIN STUDIES 



the differences in the fermentation of lactose and saccharose as 

 a distinguishing feature between the American and French or- 

 ganisms since they say that not all their strains fermented 

 saccharose. Meyer and Aird have shown conclusively the in- 

 constancy in fermentative powers of not only many American 

 strains but also of different French strains. They conclude 

 it is impossible to differentiate sporotricha into two distinct 

 species by means of the fermentation of carbohydrates. These 

 results have been confirmed by the writer. Greco's observa- 

 tion on a South American strain does not agree with those of 

 de Beurmann and Gougerot on French strains. 



Specific serum and dermal tests are probably of limited 

 value in differentiating these closely related organisms though 

 they may furnish important data for the basis of a group 

 relationship. So far as the results indicate they show 110 dif- 

 ferences between the French and American strains. 



From the above analysis it would seem that the basis upon 

 which French investigators differentiate the Sporotrichum 

 schenckii and Sporotrichum beurmanni is, to say the least, 

 very inadequate. On account of the pleomorphism of this 

 organism there is an excellent opportunity to take advantage 

 of slight and unimportant differences in order to create new 

 species. It is of course true that no two strains are exactly 

 identical. De Beurmann and Gougerot noted that certain 

 of their strains manifested fixed pleomorphic changes that 

 made them appear identical with the original Sporotrichum 

 schenckii. Yet they did not suggest that these strains be 

 called Sporotrichum schenckii. Concerning these slight dif- 

 ferences, especially in organisms of this type, it would seem 

 that it would be wise to assume a conservative attitude and 

 to refrain as much as possible from the use of new and un- 

 necessary terms. 



The question arises in connection with an organism of this 

 kind, as it arises so frequently in biology, what differences 

 are sufficient to warrant the creation of a new variety or 

 species? Where shall the line be drawn between varieties 

 since no two cultures of sporotricha are absolutely identical 

 in every detail and strains are ever prone to these striking 



