31] PROTEOCEPHALIDAE — LA RUE 31 



the product of the vitelline glands. The ootype is a slightly elongated 

 muscular organ of small size. Its muscles are much heavier than those 

 of the oviduct and they represent, perhaps, a higher development of the 

 oviductal muscles. About the ootype is found a large number of long 

 slender cells which in the aggregate have been called the shell-gland. 

 Each cell evidently discharges by its own minute duct which may be 

 traced well down between the muscles of the ootype. In the ootype the 

 egg is formed. The ootype discharges directly into a duct called the 

 uterine passage. This duct leads forward directly or after a few coils 

 have been described and discharges the formed eggs into the median stem 

 of the uterus at a point which is usually anterior to the posterior end of 

 the uterus and on the dorsal side of the latter. In structure the uterine 

 passage differs from the oviduct in the lack of strong musculature. Some- 

 times it is difficult to find any musculature at all. There are scattered 

 gland cells and numerous nuclei of cells which are of an epithelial nature 

 or which belong to cells of parenchymatous origin. These structures of 

 the interovarial space have been worked out by Monticelli (1891), von 

 Linstow (1891), who made numerous errors; by Kraemer (1892), who 

 likewise made some errors. Riggenbach (1896) did very careful work 

 and so also did Benedict (1900), altho the latter erred in denying the 

 existence of a uterine passage for his species. More recently the writer 

 (La Rue 1909) has worked out all these points in considerable detail. 



In all the species of the family the uterus develops as a median 

 longitudinal tube (Fig. 105) lying in the medullary parenchyma just 

 within the longitudinal muscle sheath and toward the ventral side of the 

 proglottid, while the testes occupy the field toward the dorsal side of the 

 proglottid. This long tube extends almost from the anterior end to the 

 mid-piece of the ovary. The stem of the uterus is first seen as a rod of 

 deeply staining cells which seem to arise from differentiating parenchyma 

 cells in young proglottids. The rod after a considerable multiplication 

 of cells becomes hollow throughout its entire length. By the method of 

 outpocketing described by La Rue (1909) the uterus sends out a few 

 or numerous branches to the right and left. These branches begin as 

 rods of cells which rapidly multiply. Then a cavity opens through the 

 length of the rod somewhat as the lumen appears in smaller blood ves- 

 sels during the development of higher animals. The rod continues to 

 increase in length and the lumen to extend as the rod lengthens. A few 

 of the outpocketings are directed ventrally and these eventually pierce 

 the ventral body wall (Fig. 89) and thus provide opportunity for the 

 discharge of eggs. The lateral pouches are formed prior to the dis- 

 charge of eggs into the uterus and in all cases observed the pouches in- 

 creased in size so rapidly that there was no crowding of eggs until the 



