304 THE ANATOMY OF CESTODES. 



the suckers, a regular network, which unites into larger stems as it 

 leaves the suckers. In the spaces between the suckers the vessels 

 anastomose. Here originate the longitudinal stems of the body. In 

 Tccnia perfoliata I observed only two stems, 1 one of which ran down 

 each side of the middle layer of the body. The thickness of the walls 

 is considerable. In every joint the longitudinal canals give out 

 branches, which ramify." 



And it is not only fluids which find their way through the pores 

 of the suckers, but formed substances, " roundish bodies of the size of 

 blood or chyle corpuscles." These are found in the intestinal mucous 

 membrane of the host, and are probably nothing else than blood and 

 chyle corpuscles. They are very frequently found in the interior of the 

 suckers, which are sometimes quite full of them. Blumberg thinks 

 that he has also found these corpuscles in the vessels of the suckers, 

 and followed them on their way to the interior ; but I must confess that 

 I am of Kahane's opinion, who identifies these so-called corpuscles with 

 cross sections of muscles, and regards the contents of the hollow of 

 the suckers merely as epithelial cells and their remains. After all 

 this, I see no reason for renouncing the old opinion as to the vascular 

 apparatus found in the Cestodes ; and the less so since this apparatus 

 has been shown by the elder van Beneden to be most thoroughly 

 homologous with that occurring in the Trematodes, where the presence 

 of an intestine shows, more distinctly than in other cases, that it is to 

 be regarded as an excretory apparatus. 



The Sexual Organs. The structures which we have been consider- 

 ing extend throughout the whole body of the tape-worm, although the 

 various parts may exhibit many differences in the nature and perfec- 

 tion of their development. But it is quite otherwise in regard to the 

 last organ which we have to describe ; the great distinction being, 

 in a word, that though common to the joints, it is completely absent 

 from the so-called " head" of the tape-worm. It is true that at first the 

 proglottides are without sexual organs. But their asexuality has only 

 a short duration. As soon as a definite size is reached, the sexual de- 

 velopment begins just as is the case in many of the lower animals. 

 The separate parts originate in definite succession, they grow, they 

 perform their functions, and ultimately attain so large a size that 

 the other organs of the Cestode body are quite dwarfed. The 

 uterus is developed most of all, and by the accumulation of 

 the hard-shelled ova it assumes a more or less brownish colour, 

 and renders the appearance of the otherwise peculiar mature 

 joints very striking. This is especially true of the larger species, 



1 This is a mistake, for four longitudinal stems Can be plainly distinguished. 



