absorbed by the walls of the intestine among the parts of the body of the 

 animal is attained by this means. The structure of the intestinal wall, as 

 the researches of Goto show, can be of two types. The first type is 

 characteristic of Microcotylidae, Mazocraeidae, Diclidophoridae, and 

 Hexabothriidae , and is distinguished by the fact that there is no continuous 



Fig. 65. Anclyodiscoides siluri 

 (Zandt), adult worm from the 

 gills of Silurus glanis L. from the 

 Delta of the Volga. 



Fig. 66. Microcotyle reticulata 

 Goto, adult worm. Natural size 6- 

 10 mm (According to Goto, 1894). 



epithelium in the intestinal wall but instead isolated large epithelial cells 

 with numerous pigmented granules are situated upon the tunica propria 

 (Fig. 67). The second type peculiar, according to Goto, to Gyrodactylidae 

 Dactylogyridae, Monocotylidae and Capsalidae, is represented more or 

 less by a typical cuboidal or columnar epithelium sometimes arranged in 

 several layers (Fig. 68). For the forms of the first type, the absence of 

 salivary glands of the esophagus is characteristic; for the second, their 

 presence. Apparently, both types of digestive tracts are linked with differ- 

 ent means of digestion. For the first type, digestion probably occurs in- 

 side the intestinal canal, in the second type --intracellular, by way of active 

 seizure of food particles which are prepared by the "salivary" glands. The 

 picture of the intracellular digestion can be well observed in a number of 

 forms, particularly among Polystomum integerrimum Froelich (Fig. 69). 

 As a matter of fact, this question demands further special investigation. 



p. 49 



43 



