GENERAL CONSIDERATIONS. 



211 



at one point the ascending and descending portions approach each 

 other. As the bent part widens at the same time, fusion and 

 perforation of the wall of the uterus takes place, so that the parts 

 of the uterus in front of and behind the bend enter into direct com- 

 munication. From this point, however, two canals lead into the 

 widened portion of the uterus, which has thus become vesicular, 

 and forms the receptaculum seminis. 



The receptaculum ovorum arises between the receptaculum seminis 

 and the ovary as a hernia-like outgrowth of the uterus (or oviduct). 

 When this has attained a certain size, the epithelium at its point 

 is said to rupture (v. Kennel), the so-called ovarial funnel of 

 Gaffron thus arising. This funnel, however, is not, as this author 

 assumes, open towards the body- 

 cavity, but remains covered by the 

 connective tissue which invests the 

 uterus (v. Kennel). 



These points seem to require re-investi- 

 gation. In the meantime, Sedgwick's 

 conjecture that the receptaculum ovorum 

 corresponds to the terminal sac of the 

 nephridium of the genital segment seems to 

 merit attention.* 



v. Kennel agrees with Sedgwick as to 

 the formation of the genital glands in so far 

 .as he also derives them from the dorso- 

 median portion of the primitive segments, 

 but, if we understand him rightly, he 

 thinks that the dorsal portions of only tivo 

 primitive segments, viz., those belonging to 

 tlie genital segments, take part in the 

 process ; these remain united with the 

 lateral portions (Fig. 105 A-C),a,s Sedgwick 

 also showed. 



General Considerations. 



The possession of tracheae and seg- 

 mentally arranged nephridia brings 

 Peripatus into relation with the 

 Arthropoda on the one hand and the 

 Annelida on the other. In addition 

 to these two principal characters, 

 Peripatus has a number of other 



Fir.. 105. — Diagrammatic sections 

 through the genital segment of 

 female embryos of P. Edwardsii at 

 various ages (after v. Kennel, from 

 Land's Text-book of Comp. Anat.). 

 d, intestine ; ee, nephridia] canal 

 (arising through an invagination of 

 the ectoderm); ml, mesodermal por- 

 tion (funnel) of the nephridium ; n, 

 ventral nerve-trunk; ov, ovary (dorso- 

 median portion of the primitive seg- 

 ment) ; V", vagina (unpaired ecto- 

 dermal invagination). 



* [Wiii.f.y (App. to Lit. on Onychophora, Xo. II.) supports Sedgwick's 

 views. — Ed.] 



