PHYLUM ANNULATA 



463 



the capsulogoiiouH gliiiuls (p. 457), situated in tlie neighbourhood 

 of the re[jr<iihicti\t' organs. The s2jeruis from the male apertures 

 of eaeh pass along temporarily formed gi'ooves to the rccepturula 

 semiiiis of the other. 



When the ova are raatm-e they are discharged from tlie ovary 

 into the cavity of the thirteenth segment, whence they pass out 

 to the exterior through the oviducts, to be enclosed in the cocoon 



m.es 



blast op 



ncj' 



Fti;. 3fi4. — Earl.v stages in the development of Iiumbricus. ^.lateral view of flattened blastula ; 

 B. ventral view of gastrula with slit-like blastopore ; C, lateral view of later stage, blastoc, 

 blastocoele ; blastop. blastopore ; r^rt. ectoderm ; eivl. endoderm ; m. primary mesoderm cell ; 

 mes. mesoderm bands ; ii-ic. cell from which the primitive nerve-cord (ne. co.) takes origin ; 

 nplt. cells taking part in the formation of the nephridia ; st. stoniodffium. (After Wilson.) 



(vide infra), after having being detained for a time in the 

 receptaculum ovorum. 



Development. — The oosperms or fertilised ova of the Earth- 

 worm are enclosed, together with a quantity of an albuminous fluid 

 derived from the capsulogenous glands, in a cocoon, the wall of 

 which is formed of a viscid secretion from the glands of the 

 clitellum, hardened and toughened by exposure to the air. The 



