Frona our point of view, the main statement of the author, 

 which deserves very minute attention, is the thesis that the(**) establish- 

 ment of the parasite in the host organism arises anew each time in the 

 ontogenesis of the corresponding pair, in ether words, "the process of 

 effectuation of the organism (adaptation to the host?, nobis) by the parasite 

 is synchronous to the present period of evolution of life on earth. " It is 

 completely correct that E. N. Pavlovsky underlines that in each case the 

 conditions of the origin of this new pair depend upon "a large number of 

 causes connected with both coinponents of the system, both in their present 

 as well as in their evolutionary past (the italics are oars--B. B. ). Ex- 

 amining the contemporary processes E. N. Pavlovsky shows that for 

 realization of the process of the formation of the pair, parasite-host, the 

 presence of three groups of factors is necessary: 1) those predisposing the 

 organism to its infection by particular parasites; 2) those determining the 

 possibility (**) of the establishment of a particular parasite in the host 

 individual (actually Bychowsky wrote, "possibility of the formation of the 

 individual by the host of a determined parasite, " nobis ); 3) factors per- 

 mitting the(**) establishment of the parasite in the host organism (reactions 

 of the exterior medium according to E. N. Pavlovsky), 



Thus, according to E. N, Pavlovsky only th:; combined action 

 "of the triad of factors insures the establishment of the pair, parasite - 

 host." This scheme represents a change of the "triad" proposed earlier 

 by E. N. Pavlovsky and V. G. Gnezdilov (1939) for parasites entering the 

 host organism through the mouth. One cannot fail to note that it represents 

 the reflection of a dialectical conception of the process of transformation 

 of a possibility into actuality and by that very fact produces on the reader 

 a very tempting impression. However, it is indispensable to stop briefly 

 on the questions arising in the examination of each one of the members of 

 the "triad" of Pavlovsky. 



Speaking about predisposing factors, as "the first member of the 

 triad," E.N. Pavlovsky refers to such, the peculiarities of the structural, 

 physiological and biochemical nature of the host organism which allow the 

 future parasite to utilize the given organism as a host. In other words, he 

 accentuates the peculiarities of the medium of the first order (in relation 

 to the parasite, see Dogiel, 1947), without explaining especially the 

 peculiarities of the parasite which allow it to utilize a particular medium 

 of the first order. At first glance this is a play on words inasmuch as the 

 statement of the question by Pavlovsky, it would seem, presupposes also the 

 peculiarities of the parasite; however, this is incorrect. To predisposing 

 factors in equal measure must be ascribed also the structural and physio- 

 logical peculiarities of the future parasite which allow it to utilize a certain 

 organisnn as a host. Moreover it seems to us that in the first place it is 

 indispensable to consider the peculiarities of the parasite in order to under- p. 287 

 stand the process of establishment of the organism in its host. Conse- 

 quently, it is not accidental that in the general discussions arising about 



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