RENAL AND REPRODUCTIVE SYSTEMS. 455 



the lungs, and note the openings of the various air-sacs described 

 above (pp. 435-438). 



VII. DISSECTION OF THE RENAL AND REPRODUCTIVE 

 SYSTEMS. 



These may conveniently be considered together, because, 

 as in the rabbit, the genital ducts are in both sexes formed 

 from what were originally parts of the excretory system. 



In the male the vas deferens is formed from the meso- 

 nephric or Wolffian duct ; in the female the oviduct is formed 

 from the Mullerian duct. In both sexes the kidneys and 

 ureters of the adult are formed on each side from the hind- 

 most division of the kidney of the embryo, i.e. the meta- 

 nephros. and the metanephric duct. 



A. The Male Pigeon. 

 1. The renal system. 



a. The kidneys are a pair of solid three-lobed bodies, 



lodged in cavities bounded by the ilia and 

 sacrum, immediately behind the lungs. Their 

 ventral surfaces are covered by peritoneum. 

 There is no distinction between cortical and 

 medullary portions, and no ' pelvis.' 



b. The ureters are a pair of straight narrow tubes. 



Each arises in the substance of the anterior lobe 

 of its kidney, emerges between the anterior and 

 middle lobes, and runs backwards along the inner 

 side and ventral surface of the middle and 

 posterior lobes, and then straight back to the 

 dorsal wall of the cloaca. 



Slit up one of the ureters, and follow it into the anterior 

 lobe of the kidney, noting the openings of smaller ducts into it 

 at intervals along its length. 



c. The adrenals are a pair of small elongated yellowish 



bodies, attached to the ventral surface of the 



