8 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.60. 



beginning of that duct. The short germ duct is joined by the vitel- 

 line ducts as it enters the shell gland. It then turns in its course, so 

 that, as the oviduct, it leaves the shell gland, it is near the point 

 where the germ duct has its beginning. These structures form a 

 compact mass and the sections tlu^ough them are not easy to interpret. 



The germarium occupies a little less than the middle third of the 

 posterior portion of a mature proglottis in which but few eggs 

 have accumulated in the uterus. Its antero-posterior diameter is 

 equal to about two-thirds the length of the proglottis. At either 

 side of the median line it fills all the space in a dorso-ventral direc- 

 tion within the layer of longitudinal muscles. 



The shell-gland is situated on the median line near the posterior 

 end of the proglottis, and is surrounded by the germarium. It is a 

 compact gland made up of large, oval, or pyriform cells, deeply 

 staining in haematoxylin. The diameter of the cells of the germa- 

 rium was found to be 006 mm., while the cells of the shell-gland 

 were 0.009 and 0.015 mm., in the two principal diameters. 



The uterus in immature proglottides is represented by an elon- 

 gated mass of cells lying on the ventral side along the median line 

 (fig. 11). It comes to occupy more and more space as the proglottides 

 mature, and in ripe proglottides practically all of the interior is 

 filled with eggs. The eggs are very small and nearly circular in 

 outline. They measure from 0.012 to 0.015 mm. in diameter. 



The vitellaria are distributed along the ventral side of the 

 proglottis next within the longitudinal muscle layer. In haema- 

 toxylin-stained sections they are not differentiated from the testes 

 and germarium, but can be distinguished readily from the former by 

 the smaller follicles, and from the latter by the irregular outlines of 

 the cells, and, in mature proglottides, by the fragmented condition 

 of many of the cells. In a section of a proglottis, in which eggs were 

 beginning to appear, the diameter of the vitelline follicles was about 

 0.03 mm. while the diameter of the testicular follicles was 0.10 mm. 

 In sections stained with indigo-carmine the vitellaria are well dif- 

 ferentiated. Transverse sections show that the vitellaria take up 

 much less of the thickness of the proglottis than do the testes, while 

 their distribution laterally is about the same. 



