146 



PRACTICAL PABASITOLOGY 



glands mature first and this maturity is followed by copulation, 

 generally reciprocal. The ripe spermatozoa are stored in the recepta- 

 culum serninis, a special enlargement of the vagina, until the female 



glands are ready to supply their products 

 the ovary the eggs, the yolk-gland yolk- 

 cells. The fertilized ova pass into the 

 uterus, causing it to unfold, while more or 

 less complete retrograde changes take place 

 in the germ-preparing glands, beginning 

 with the testes. In the oldest ripe proglot- 

 tides of the larger Taeniae, all that! remains 

 of the sexual organs is the cirrhus-pouch, 

 portions of the vas deferens and vagina, 

 traces of the shell-gland, and the completely 

 developed uterus. The uterus is composed 

 of a main stem running from front to back 

 in the median line, from which are thrown 

 out on both sides a quantity of ramifying 

 branches with blind ends, the number of 

 which varies in different species. The rami- 

 fications of the uterus, together with the 

 shape, size, number and arrangement of the 

 hooks on the rostellum, are points of impor- 

 tance in distinguishing between species. 



If a ripe proglottide of one of the larger 

 Taenise of man, the dog or the cat, is pressed 

 between two glass-slides and held up to the 

 light, the uterus, which may be seen with 

 the naked eye, will appear as an opaque tree- 

 like structure in a transparent field. The 

 appearance of the uterus in ripe segments 

 of Dipylidium caninum, however, is quite 

 otherwise. It is best seen in mature seg- 

 ments which have been carefully stained and 

 coloured, where it has the formation of a 

 net, in the meshes of which the testes are 

 placed. After the entrance of the eggs, the 

 uterus breaks up into parts, each containing 

 several eggs, and a reddish granular mass 

 is secreted, which encloses the eggs and 

 cements them together in masses. After 

 the disappearance of the uterus-wall, these egg-clusters lie free in the 

 parenchyma and this gives to the ripe segments a reddish colour. 

 The egg-clusters are easily obtained by teazing out a ripe joint (fig. 36). 



FIG. 66. Head and neck 

 of Tfsnia solium, L., show- 

 ing th,e appearance of the 

 head in the large-hooked 

 varieties of the Taenise of 

 mammals. 45 : 1. 



FIG. 67. Two mature pro- 

 glottides of Tcenia solium, 

 showing the arrangement of 

 the sexual organs in the large- 

 hooked Tsenise of mammals. 

 Slightly magnified. 



