ORGANIC EVOLUTION 



189 



FIG. 116. Diagram of the 

 relations of renal and repro- 

 ductive organs in amphi- 

 bians, male above, female 

 below, k, k, kidneys; , u, 

 ureters;' cl, cloaca; 5, 5, sper- 

 maries (testes). Arrows in- 

 dicate the course of the 

 sperm ducts through the 

 kidneys to join the ureter; 

 a, a, fat body; o, o, ovaries; 

 d, d, oviducts; /, /, their 

 funnel shaped openings into 

 the coelom; t, t, the dilata- 

 tion(uterus) at the lower end 

 of each. 



blackish pigment as they increase in size, studding the 

 transparent membrane. The eggs are shed from the 

 ovaries into the body cavity and the ducts by which they 

 reach the exterior are not connected to the ovaries at all. 

 The oviducts are long sinuous tubules extending the whole 

 length of the body cavity near the mid-dorsal line, opening 



by a V-shaped 

 slit at the an- 

 terior end that 

 is situated be- 

 tween the esoph- 

 agus and the 

 shoulder, and 

 into which the 

 eggs find their 

 way, aided by 



the lining cilia. As the eggs pass down 

 the tube a gelatinous secretion is added 

 to them by cells along the way, and 

 they find temporary storage in a sac- 

 culation (uterus) at the lower end of the 

 duct just before it enters the cloaca. 



Nervous system. As already noted, 

 the central part of the nervous system 

 in the salamander, as in vertebrates 

 generally, is lodged in the body wall 

 upon the dorsal side. It consists of a 

 hollow, but thick walled tube of nervous 

 matter, differentiated into two principal parts: a consider- 

 able enlargement, the brain, is lodged in the cranial cavity 

 of the skull, and a long spinal cord occupies the channel 

 formed by the annular vertebras. The branches it bears, 

 and by which it maintains communication with peripheral 

 parts of the body are paired nerves, which it gives off 



