576 



THE AMEBIC AN NATURALIST [Vol. XLIV 



what these conditions or stimuli are, is exceedingly difficult, even 

 though we assume in the beginning that the organism under in- 

 vestigation has no latent hereditary possibilities of change in- 

 directly or not at all dependent upon its immediate environment. 



Our work with Gloposporium and Colletotrichum, part of 

 which is yet unpublished, indicates that so far as these organisms 

 are concerned, at least, no such method would prove practicable; 

 as the same organism, so far as any morphological characters or 

 host relations serve to identify it, will frequently behave very 

 differently when cultures of the organism obtained from differ- 

 ent acervuli on leaves of the same host are made. This fact 

 might be easily explained, perhaps, by the assertion that such 

 forms are the elementary species of DeVries and others, or races 

 or strains, but this rather complicates than amplifies the prob- 

 lem. If there are numerous elementary species of the same 

 fungus to be found on the same host without recognizable morph- 

 ological differences, it is certainly questionable whether any 

 practical taxonomic work could be founded upon such a basis. 

 Until it can be demonstrated that an organism is entirely con- 

 trolled by its external environment and nutritive conditions and 

 all its hereditary expressed and latent characters are known, it 

 will be hazardous to base positive conclusions upon such data. 

 We must continually keep in mind and be prepared to make al- 

 lowance for the inherent hereditary characteristics and possi- 

 bilities of the organism which may possibly find expression in 

 any particular individual or generation. 



The vast and complex problems of determining the origin and 

 cause of the form and behavior of even the simplest living organ- 

 ism is not perhaps to be so easily solved. The more it is studied 

 the more difficult it appears. All exact knowledge and data in 

 regard to these phenomena are to be welcomed, however, and the 

 more we come to appreciate the difficulties of the subject the 

 better able we should be to devise experiments that will yield 

 the necessary data which may eventually reveal to our finite 

 minds some of these profound mysteries of nature. 



