EARTHWORM. 19 



ous glands: small pouches attached to the 

 sides of the oesophagus. 

 Observe : 



(a) The seminal vesicles : three pairs of rela- 



tively large, opaque white bodies lying 

 at the sides of the oesophagus. In the 

 mature worm the posterior pair grow 

 together, forming a posterior median 

 vesicle lying ventral to the alimentary 

 canal in the llth somite ; and the two 

 anterior pairs in a similar way form 

 one anterior median vesicle in the 10th 

 somite. Cut off the tip of one of the 

 vesicles, mount in water on a slide, and 

 examine with the high power. Look 

 for different stages in the development 

 of the spermatozoa. (Cf. " General 

 Biology," Sedgwick and Wilson, second 

 edition, p. 77.) 



(b) The funnels ("ciliated rosettes") of the 



vasa deferentia (seen in the mature 

 worm by carefully opening the median 

 seminal vesicles) : two pairs of rosette- 

 like bodies with opaque white borders 

 in the 10th and llth somites. 



(c) The vasa deferentia: four fine ducts run- 



ning posteriorly from the four funnels. 

 The two of the same side unite in the 

 12th somite to form a single duct on 



