364 ANIMAL PARASITES. 



transversely. Four tubiform longitudinal muscles originating 

 from the ridges of corium, at the mouth are peculiarly interest- 

 ing. They pass down to the tail, forming two ventral and two 

 dorsal muscles, which diminishing anteriorly and posteriorly and 

 becoming amalgamated with the corium, leave free band-like stripes 

 between them. The muscular canals consist of a longitudinally 

 striated, or, more correctly, longitudinally folded sarcolemma, 

 which separates in water and by coagulation, of an inner, tena- 

 cious, fluid substance with peculiar fround, biscuit-shaped) corpuscles 

 (of a fatty lustre, moveable by pressure, and becoming converted 

 into transverse plates by coagulation), and of a somewhat dark, 

 homogeneous basal substance (ligamentous substance, muscular 

 fibrine) which forms a solid cylinder in the interior of the muscle. 



In the earliest period the four longitudinal muscular canals 

 were four sarcode canals, which become converted into muscu- 

 lar canals from the apices towards the middle. At a later 

 period, the sarcode is entirely deficient in the muscles, and dis- 

 appears generally from the moment when the nerves show them- 

 selves. As long as they are still sarcode canals large cells are 

 seen in them on contact with water ; these possess a nucleus which 

 is reddish by transmitted light, and one or two round or biscuit- 

 shaped nucleoli, which finally, by long contact with water become 

 pale and decrease until there is nothing of them but a shiny cor- 

 puscle in a delicate membrane. Without the application of water, 

 large acellular, albuminous drops are found in them; these flow out 

 when the animal is cut through, and acquire all sorts of amseboid 

 forms, which, however, always revert to the round or oval form 

 and exhibit the clear contents with a reddish nuclear vesicle. 



We must again revert to the four free, band-like stripes 

 which exist between the muscles, and of which there are two on 

 the sides, one on the ventral surface, and one on the back. In 

 the young state they form canals filled to overflowing with fat. 

 With the advancing development of the animal, the fat gradu- 

 ally disappears ; and in fully developed individuals, only single 

 drops are seen from time to time, and the canals are generally 

 empty and folded, and have become wrinkled, empty whitish 

 cords. They run from the head to the caudal extremity, and 

 become united like the muscles with the corium. The branch 

 running along the ventral surface bends round the various ori- 

 fices occurring on this surface. There is certainly no doubt 

 that these four fat-canals assist in the development of the animal, 



