PROTEOCEPHALUS AMBLOPLITIS LEIDY 

 SESSIONAL PAPER No. 39b 



179 



Above Table shows the occurrence of the plerocercoid in visceral organs of nine 

 specimens of M. dolomieu. 



From this it is seen that there is considerable variation in the numbers of the 

 plerocercoid infecting the different organs: there is also a variation in their size. 

 Those found in the stomach are very few in number and quite small. The intestine, 

 on the other hand, harbors most of the plerocercoids found in the alimentary 

 tract, their size ranging from 0-5 cm. to the adult condition (vide infra). Most 

 of those found in the liver (PI. XIX, Figs. 2, 3, 4 and 5) which, like the livers of 

 most fishes harboring larval cestodes is much infested, average about 1 cm., 

 the limits being from less than 1 mm. to 2 or 3 cms. as dissected out without 

 the use of a lens or dissecting microscope. The smaller specimens are more cylin- 

 drical and compact in their structure than are the larger ones, the latter being, 

 as Leidy describes them, "soft and white." The plerocercoids found in the 

 ovaries and testes are somewhat flattened behind the constriction between the 

 scolex and the body, soft and distended as if well provided with nutriment, that 

 is, the constriction itself is deeper and the apex of the scolex is also better de- 

 veloped than in those found in the other of the visceral organs (PI. XIX, Fig. 6). 

 The scolex is attached to the outer wall or stroma of the gonad, while the body 

 lies free away among the eggs or sperms, as the case may be, thus surrounded 

 with a rich nutritive medium. The presence of such a food supply doubtless 

 accounts for the greater diameter, the length remaining more nearly the same 

 for similar stages of development. Furthermore the plerocercoids found in the 

 gonads are on the average much larger than those found in the other viscera, 

 another point which illustrates the influence of the surrounding tissue on the growth 

 396—12 II 



