875 species of tapeworms known up to that time fronn 850 species of 41 (sic) 

 orders of birds, showing that there is practically no exception to the rule 

 advanced by him. One can hardly disregard this fact especially since sub- 

 sequent serious research confirms the same normalities (regularities, 

 principles, nobis) concerning tapeworms parasitizing birds. However, 

 numerous facts are known about the finding of single species on several 

 orders, and these cases form the two types--the first in which the species 

 is encountered in representatives of orders related to each other and the 

 second- -on birds which have a close biology and composition of food but 

 which pertain to unrelated orders (M, N. Dubinin, 1950, 1951, 1953b). If 

 one can consider the first type as not contradicting "the rule of Fuhrmann" 

 in essence, the second on the other hand appears as a real exception. 



However, before considering this as final, one must say that to 

 Fuhrmann is ascribed (the view, nobis), completely unconvincing ly from 

 our point of view, that he "considers the distribution of tapeworms in 

 different orders of birds as something pre-established, congealed, in an 

 arrested state of development, something determined" (Markov, 1948). 

 Where does this idea come from? Is it from the fact that to Fuhrmann 

 was ascribed a statement that: "The representatives (of the helmintho- 

 fauna of determined orders of birds) cannot parasitize the birds of other 

 orders"? But actually Fuhrmann doesn't say anything definite about the 

 reasons which cause a determined distribution of tapeworms among their 

 hosts but only expresses a supposition that it will be possible to show 

 later that consanguinous relations of the hosts (historical factors) play a 

 more important role than the geographical and ecological factors in the 

 nature of the distribution of separate species of tapeworms in the 



orders of their hosts--birds. This can hardly be understood as justa- 

 position of "naysterious phylogenesis--biological factors" (Markov, 1948). 

 However, we shall return later to the question on "mysterious phylo- 

 genesis" (see page297 ). 



It seems to us completely correct that to evaluate the causality p. 296 

 of the "rule of Fuhrmann" by M. N. Dubinin (1953a); "it is completely 

 normal (regular, nobis ) that natural taixonomic groupings of animals (order- 

 family-genus), which more often embrace species which are sinralar in 

 alimentation and form of life, have a more or less similar parasitofauna 

 and contain a large number of common parasites. " These considerations 

 are fully acceptable for many groups of endoparasitic animals to which, 

 in this connection but with different limitations, "the rule of Fuhrmann" 

 can be applied. Thus, the rule generally corresponds to the facts and in 

 the present level of knowledge can be accepted, understandably- -not as 

 all-embracing, but as one of the rules about occurrence of endoparasitic 

 animals on their hosts. The categoric nature attributed to it is not 

 legitimate and does not speak against Fuhrmann but against his unusually 

 zealous followers and adversaries. Thus, Charles Darwin cannot be 

 blamed if his teaching is perverted by facist-social darwinists and in the 



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