380 CRKS8WEI.L 8HEAKER. 



tliey discharge into the vesica he, K;ich glund is composed 

 of about twenty cells, arranged in a single layer, laterally, 

 against the wall of the segment. They fill up the greater 

 part of the middle third of the region. They commence 

 anteriorly, just behind the orifice of the retracted claspers, 

 and stretch back to a point, on a line behind the vesiculae 

 on either side. J)orso-ventrally they extend from the border 

 of the dorsal longitudinal muscles round the sides of tlie 

 segment to the border of the ventral bands. IMieir cells 

 have a waxy appearance, and their cytoplasm, which is rela- 

 tively large in amount, is very finely granular. Each cell 

 possesses a round nucleus and a dark karyosome. On a line 

 with the vesiculas the dorsal cell of each group gives off a 

 fine duct, that crosses the space of the testis cavity and runs 

 into the ventral external surface of the vesicle of the same 

 side. The wall of this tube is also, like the protoplasm of the 

 cells of the gland, fineh' granular. About its middle there 

 are usuallv two laro-e nuclei embedded in the wall. Where 

 the tube runs round the outer surface of the vesiculae it is 

 much thickened, and this appears to be due to the accumulation 

 of drops of the gland secretion in its lumen (fig. 31). 



The vesicular are roundish bodies with thin walls. The 

 lateral and ventral third of their cavities is taken up with 

 the mucous secretion derived from the granule glands. This, 

 in sections of fixed material, projects upwards into the cavity 

 in a mass of finger-like digitations. On the outer ventnil 

 surface of each vesicula there is a small slit. Its edges are 

 armed with short stout cilia. It was the motion cf these 

 that Foettinger evidently mistook for the presence of a pair 

 of excretory organs in this region. Through this slit the 

 spermatozoa gain an entrance into the vesiculte. 



The vas deferens leads out from the posterior ventral 

 portion of each vesicle and turns in towards the median line, 

 and is continued as a small tube to the base of the penis. It 

 is of considerable diameter, and forms a sac-like canal on 

 either side. At the base of the penis the vasa deferentia 

 of both sides meet, forming a small receptac ul urn seminis. 



