72 LECTURE IV. 



generative pores, situated upon the eminence near the middle of the 

 anterior part of the ventral surface of the segment. 



The ovaria {Jig. 32, d) are situated near the posterior margin of 

 the segment. They consist of two large transversely oblong lobes, 

 and a smaller median annular portion. They are composed of tubes 

 in which the small germinal and vitelline rudiments of the ova are 

 arranged in rows. The oviducts terminate in a long tubular uterus 

 {Jig. 32, e\ which is considerably wider than the vas deferens, and 

 advances forwards, making many transverse convolutions, the two 

 last being wider than the rest, and extending on each side of the 

 bursa penis. The ducts of a very complicated series of glands commu- 

 nicate with the uterus before its final termination at the vulva or pore, 

 which is behind the male opening. The glands just alluded to form 

 a stratum next beneath the skin at the sides of the joints. Eschricht 

 calculates that there are 1200 of these glands in each joint. In the 

 joints furthest from the head, containing the mature ova, these glands 

 become filled with a thick yellow matter which they pour into a 

 system of ramified ducts, which unite to discharge themselves in the 

 dilated part of the uterus. Their office seems to be to cement together 

 the ova in hard cylindrical masses by forming a crust around them, in 

 which state they are found in the detached joints. This is the first 

 example we have yet seen of nidamental glands, which we shall sub- 

 sequently find to be a conspicuous part of the generative organs in 

 many oviparous Invertebrata. 



From this description it will be seen that the proportions and 

 almost the forms of the ovarium and testis, are reversed in the Bo- 

 thriocephalus and Tcenia : the positions of the sexual outlets are 

 unquestionably very different in the two genera. Both, however, 

 agree in presenting the most extensive development and preponder- 

 ance of the generative system that is known in the Animal Kingdom. 

 In fact there is scarcely space left in the hinder joints of the tape- 

 worms for the organs of any of the other systems. 



The natural rate of life of a tapeworm, the consequences to the 

 remaining adherent part of the repeated detachment of the ovigerous 

 segments, the extent to which they are detached and subsequently 

 renewed, have not yet been, nor are likely ever to be, the subjects 

 of direct observation in these internal parasites of man. 



Some highly interesting facts have, however, been made known by 

 the same professor, to whom v/e are indebted for a knowledge of the 

 anatomy of the Bothriocephalus latus, in the economy of another 

 species of Bothriocephalus (B. pwictatus) which is extremely 

 common in the small sea-fish called Cottus scorpius. 



During midsummer these tapeworms are fully developed, and their 



