PROTO TRA CHE A TA. 



285 



each lies constricted off from its neighbours. When born the young 

 resemble the parents except in size and colour. In P. novce zealandicc 

 the ova pass from the ovary into the uterus in December, and the young 

 are born in July — a long period of gestation. 



(b) Male (of P. edwardsii). — The male elements are produced in 

 small testes, pass thence into two seminal vesicles, and onwards by two 

 vasa deferentia into a long single ejaculatory duct, which opens in front 

 of the anus. In the ejaculatory duct the spermatozoa are made into a 

 long packet or spermatophore, 

 which is attached to the female 

 during copulation. 



While it is characteristic of 

 Arthropods, in which the develop- 

 ment of chitin is so predominant, 

 that ciliated epithelium is absent, it 

 seems that in Peripatus, which is 

 much less chitinous than the others, 

 ciliated cells occur in some parts of 

 the reproductive ducts, and perhaps 

 also at the internal funnels of the 

 nephridia. This is indeed what one 

 would expect. 



Development. — There is great 

 variety of development in different 

 species. Thus there is much yolk 

 in the ovum of P. novce zealandice, 

 extremely little in that of P. capensis. 

 In the former species the yolk has 

 a manifold origin ; it is said to arise 

 in the protoplasm of the ovum itself 

 from the breaking up of the germinal 

 vesicle, from surrounding follicle 

 cells, and from yolk present within 

 the ovary. In P. capensis and 

 /'. balfouri spermatozoa reach the 

 ovary, and there probably the ova 

 are fertilised, but in P. nova 

 zealandice the spermatozoa are con- 

 fined to the receptaculum seminis, 

 near which fertilisation seems to 

 occur. In the maturation of the ova 



of P. capensis and P. balfouri two polar bodies are extruded 

 as usual, but none have been observed in the case of P. novic 



Fig. 122. — Embryos of Peripatus 

 capensis, showing closure of 

 blastopore and curvature of 

 embryo. — After Korschelt and 

 Heider. 



a. , Anus ; 61. , blastophore ; m., mouth ; 

 p.s., primitive segments ; 7U., zone of 

 proliferation. 



zealandice. 



In P. capensis the 

 cells does not occur, 

 the usual cell limits. 



segmentation '" is remarkable, for true cleavage of 

 The fully "segmented" ovum does not exhibit 

 It is a protoplasmic mass — or syncytium — with 

 many nuclei. Even when the body is formed, the continuity of cells 

 persists, nor does the adult lack tiaces of it. To Mr. Sedgwick this 

 singular fact suggested the theory that the Metazoa may have begun 

 as multinucleate Infusorian-like animals. 



