the peculiarities of the host E. N. Pavlovsky has to terminate the section 

 on predetermining factors by passing to the evaluation of the phenomena 

 "from the (standpoint of, nobis) parasite" if one can so express hinnself 

 (1946, page 296 ). 



The factors determining the possibility of (**) the establish- 

 ment of the future parasite in the host individual (second member of the 

 triad) were characterized by E. N. Pavlovsky completely insufficiently, 

 and principally inaccurately, if one doesn't speak only about a determined 

 group of internal parasites. According to E. N. Pavlovsky the factors 

 which determine the establishment of the pair, host-parasite, basically 

 are the alimentary (food) correlations between the potential hosts and the 

 natural intermediary hosts of the parasite or other sources of invasion. 

 Actually this is a particular case which is mainly characteristic for endo- 

 parasites and even then for far from all of them. The great majority of 

 ectoparasites which have a straight or simple cycle of development reach 

 their future hosts by routes not connected with the feeding of the latter. 

 Similarly a number of endoparasites with a complex cycles of develop- 

 nnent have an active stage which infects the final host through the skin, 

 that is --also without establishment of alimentary links between the final 

 and the intermediary hosts. Consequently non-alimentary links charac- 

 terize the factors which determine the possibilities of the establishment of 

 the pair, host-parasite. But as the basic factors in this connection should 

 be considered the ones which lead to the establishment of a contact be- 

 tween the future host and the parasite, or the stages of the life cycle of 

 the first and of the second allowing the possibility of infection. Thus, the 

 second part "of the triad of Pavlovsky" is determined by the internal 

 peculiarities of the host and the parasite just as by the exterior factors 

 of the medium in relation to both of them (medium of the second order 

 according to Dogiel). 



_ 



In his dissertation, A. V. Gussew writes that the second part "of the 

 triad of Pavlovsky" represents "biocoenotic links" (page 302). This 

 undoubtedly is not accurate or, to say it nnore correctly, these links 

 represent only a part of the factors which determine the possibility of 

 infection. 



Finally, speaking about factors effectuating the (**) establish- 

 ment of the parasite in the host organism (third part of the "triad of 

 Pavlovsky"), which are determined by E. N. Pavlovsky as a reaction of 

 the exterior medium, one should keep in mind that this is hardly sufficiently 

 accurate because, along with these, the physiological condition of the in- 

 fective stage of the future parasite, which is conditioned not only and very 

 often not so much by the factors (reactions) of the exterior medium, has 

 great significance. In other words, the third part "of the triad of Pavlovsky" 



330 



