One must say that G. C. Markov does not deny the possibility 

 of conjugate evolution of the parasites and their hosts; however, he con- 

 siders that it is one way, but not the only way, of evolution and that the very 

 phenomenon of parallelism nnust be examined in a very linnited way. He 

 writes: "Its dependence (it means the evolution of the parasites --B, B. ) 

 on the evolution of the host is not subjected to doubt, and in a nunaber of 

 cases we actually observe conjugate evolution of the hosts and parasites. 

 However, even in these cases we clearly see that the parasites do not re- 

 main unchanged but undergo evolutionary influences because of the medium 

 which is external in relation to the host. " 



If basically the views of G. C. Markov are to be valued favor- 

 ably then his separate considerations demand considerable criticism and 

 considerable changes. In addition to that, the "seventh rule of ecological 

 parasitology" and its change by Markov speaks only about endoparasites and 

 does not touch upon ectoparasitic animals to which the monogenetic trema- 

 todes, which interest us, are related. 



First of all let us dwell on the notorious "rule" or of the "law" 

 of Fuhrmann. In Russian literature it is understood in the formulation of 

 K. I. Scriabin (1923) , at the same time this formulation is ascribed in 



_ 



K. I. Scriabin during the fifth parasitological convention in 1949 said 

 that Fuhrmann expressed to him such a formulation personally. However, 

 there are no publications on this subject and it is hardly permissible to rely 

 on memory, especially since the conversations between K. I. Scriabin and 

 Fuhrmann took place 35 years before the convention. 



passing to Fuhrmann by N. J. Ass, himself. In N. J. Ass' foreword, which 

 was copied from K. I. Scriabin (page 188), he expressed the views of 

 Fuhrmann and attributed them to the latter having transposed the statement 

 of Scriabin into the text of Fuhrmann (Ass, 1939 page 8). Similarly, G. S. 

 Markov cited in quotation marks "the rule of Fuhrmann" according to the formulation 

 of Scriabin. First of all, it is necessary to examine what Fuhrmann himself 

 said and to compare his formulations with that which appears among Soviet 

 parasitologists under the name of "the rule of Fuhrmann. " 



After a meticulous analysis of the literature and the miainly 

 factual museum collections of tapeworms of birds, Fuhrmann (Fuhrmann, 

 1909) came to the following conclusions: 



"1. Examining the distribution of numerous species of Taenia 

 in different species of birds we observe a very characteristic phenomenon, 

 that determined species are always encountered only in a determined group 

 of birds and are characteristic for it. " 



338 



