The opinion of Monticelli hardly corresponds to reality. The 

 remaining two points of view have sufficiently weighty evidence to support 

 them. For monogenetic trematodes we think it more probable that there is 

 no covering epithelium in the adult form, although the first point of view, 

 which is more commonly accepted, deserves more attention. The reasons 

 according to which we are led to the opinion that there is an absence of 

 epithelial cells in the adult forms of monogenetic trematodes are the follow- 

 ing. First of all, a nnajority of authors who studied the coverings of mono- 

 genetic trematodes did not discover any traces "of subcuticular cells. " p. 42 

 Thus, during the examination of over 100 species of marine Monogenoidea 

 Goto, Cerfontaine and Maclaren (Maclaren, 1903) never found them once. 



Under more careful study, the cells of the receded epithelium 

 of monogenetic trematodes, described by certain authors, appear not to be 

 subcuticular epithelium but various types of glandular cells. Until now, no 

 one has succeeded in presenting convincing views (drawings, nobis) of sub- 

 merged epithelium among Monogenoidea. The data of I. V. Ivanov (1952) 

 can be considered the only serious material on the subject. Ivanov found, 

 after becoming acquainted with our slides of Acanthocotyle , that among this 

 type, the covers as he writes, "possess all the characteristic peculiarities 

 of the classical submerged epithelium. " However, it seems to us that this 

 is not altogether accurate and that at any rate it demands more thorough 

 study. During the study of the same slides one notices that the disposition 

 of the "sub-cuticular" cells, which are clearly seen and which lie in their main 

 aggregate under the dorsal surface of the body of the animal but which can also be 

 seen as well on the ventral side, is not equal. 



Basically as is seen from Fig. 55-B, the "little stems" of the 

 cells are not linked to the cuticle but to the muscular fibers located beneath 

 it. In sections one can clearly see that the parenchyma directly joins the 

 cuticle in the spaces between the cut muscular fibers, whereas, one does 

 not observe "the little stems" of the "sub-cuticular cells" in these places. 

 Thus, so far we hesitate to speak with certainty concerning the connection 

 of these cells to the cuticle. 



Also, peculiarities of the embryology of monogenetic trematodes 

 seem to us substantial when we see that the ciliated epithelium does not 

 undergo metamorphosis at the attachment of free -swimming larva but peels 

 off completely and falls away. This pertains not only to the species where 

 the ciliated epithelium is arranged in special areas but also to the species 

 where the entire body is more or less covered with ciliated epithelium. 



From what has been said above, it is understandable why it 

 seems to us that the most probable supposition is that the cuticle of mono- 

 genetic treinatodes appears to be a derivative of the parenchyma. The pre- 

 sence of cuticular armature in a number of soecies can be considered as a 



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