30 Structure and Classification of Micro-organisms 



does not apply. Thus, for example, the fungi which, when 

 judged by other criteria, are undoubted plants, lack the power 

 of inorganic synthesis, and so resemble animals. 



Fortunately, the question is a purely academic one. Though 

 seemingly at first sight a most fundamental one, it is, in 

 reality, of trifling importance, for after a limited experience 

 the student unhesitatingly assigns most of the known or- 

 ganisms to one or the other groups, and that occasional mis- 

 takes may be made, and organisms, like the spirochaeta, 

 appear sometimes in the group of plants among the bacteria, 

 and in other writings among the protozoa, is a matter of small 

 consequence so long as the knowledge of the organisms them- 

 selves is in no particular diminished by the method of classi- 

 fication. 



In discussing the matter Delage says, ' ' The question is not 

 so important as it appears. From one point of view and on 

 purely theoretic grounds it does not exist, while from an- 

 other standpoint it is insoluble. If one be asked to divide 

 living things into two distinct groups, of which one contains 

 only animals and the other only plants, the question is mean- 

 ingless, for plants and animals are concepts which have no 

 objective reality, and in nature they are only individuals. 

 If in considering those forms which we regard as true ani- 

 mals and plants we look for their phylogenetic history and 

 decide to place all of their allies in one or the other group, 

 we are sure to reach no result; such attempts have always 

 been fruitless." 



" Huxley pointed out as early as 1876 the extremely close 

 relationship between the lowest algae and some of the flagel- 

 lates, and it is the general opinion that no one feature sep- 

 arates the lowest plants from the lowest animals, and the 

 difficulty in many cases the impossibility of distinguishing 

 between them is clearly recognized. 



' The point of view which demands a strict separation of 

 animals and plants has, however, little utility save, perhaps, 

 to determine the limits of a text-book or a monograph."* 



The relative position of the pathogenic vegetable micro- 

 organisms to the other vegetable organisms can be deter- 

 mined by reference to the following table. The wide sepa- 

 ration of the bacteria in Group II. and all of the others, 

 which appear in Group X., should be noted. 



* Calkin's, "The Protozoa," p. 23. 



