SECT. X REPRODUCTION 141 



are segmental tubes connected by a longitudinal canal 

 which acts as a common duct for all the glands. 

 These latter are branched dorsally and ventrally. 

 The branching is very rich in A. cancriformis and L. 

 productus, and in L. glacialis more so than in L. 

 Spitzbergensis. We failed to find that the branches of 

 the genital glands in one segment anastomosed with 

 those in. others, so as to form the network figured by 

 Zaddach ; but we see no reason why such anasto- 

 moses may not sometimes take place. 





Fig. 32.— Diagram of a somewhat simplified genital tube of L. Spitzbergensis or 

 glacialis, the dorso-ventral segmental tubes only slightly branched, a, aperture 

 between the loth and nth segments ; A the rudimentary part, i.e. the part 

 which lies in the posterior rudimentary segments, in which in this species the 

 epithelium breaks up into sperm cells filling up the whole lumen of the tube. 



Although there is no apparent difference between 

 the epithelium of the longitudinal canal and that 

 of the sexual glands, it is useful to consider the 

 two apart. They are both, as we have seen, formed 

 out of the peritoneal epithelium, and besides having 

 the same origin, they have the same function, viz., to 

 secrete the slime which hardens in the brood pouch to 

 form a covering for the eggs. 



It is of considerable importance for us to note first 

 of all that the sexual glands are segmentally arranged 

 in Apus. This, as far as we know, is not the case in 



