

RENAL AND REPRODUCTIVE SYSTEMS. 269 



seminales, which run straight back along the ventral 

 surface of the metanephros to open into the urino- 

 genital sinus, just in front of the cloaca. The walls of 

 the vesicula seminalis are marked by close-set trans- 

 verse lines, corresponding to internal foldings of its 

 lining membrane. 



The Wolffian duct acts as vas deferens, conveying 



the spermatic fluid from the testis to the exterior. 



Dissect the Wolffian duct of one side away from the ventral 



surface of the mesonephros, noting the tubules it receives from 



this ; and follow it back to the cloaca. 



5. The sperm-sacs are a pair of thin-walled tubes lying 

 along the ventral surfaces and the outer sides of 

 the vesiculse seminales, to which they are closely 

 attached, and which they about equal in length. 

 Each sperm-sac ends blindly in front, and dilates 

 behind to form the urino-genital sinus. 



Dissect away the sperm-sac from the vesicula seminalis 

 awl follow it back to the urino-genital sinus. 



Fio. 57. Scy Ilium canicula. Dissection of a male from the ventral 

 surface, to show the renal and reproductive systems. The left 

 lobe of the liver and the alimentary canal from the oesophagus to 

 the rectum have been removed. The excretory organs of the left 

 side only are shown. An arrow passes through the left abdominal 

 pore into the abdominal cavity, (a. m. m.) 



Fio. 58. FurtLer dissection of the renal and reproductive organs. 

 The liver and the greater part of the testis have been removed. 

 The right metanephric duct is shown in its natural position ; the 

 left duct has been displaced outwards. The urino-genital sinuses 

 of both sides have been laid open. (a. m. m.) 



AP, abdominal pore. CP, clasper. CR, groove in clasper. CS, sac con- 

 tinuous with groove in clasper. e, oesophagus. F, pelvic fin. G, gill-slit. 

 H, testis. L, liver. P, abdom nal opening of Miillerian ducts. PD, abortive 

 Miillerian duct. PG , pelvic girdle. R, rectum, rg, rectal gland.- RO, open- 

 ing of rectum into cloaca. S, Wolffian body or mesonephros. SD, Wolffian 

 duct or vas deferens. SO. opening of Wolffian duct into urino-genital sinus. 

 SS, sperm-sac. T, metanephros. TD, ureter. TD,, ducts from hinder part 

 of kidney, joining the ureter as it reaches the urino-genital sinus. TO, 

 opening of ureter into urino-genital sinus. UP, urino-genital papilla. US, 

 urino-genital sinus. VE, vasa efferentia. VS, vesicula seminalis, the dilated 

 hinder end of the Wolffian duct. 



u 



