38 



GENERAL ZOOLOGY 



the cranium posteriorly along the dorsal surface of the body cavity. 

 These trunks are connected by means of rami communicantes 

 with the spinal nerves and certain of the cranial nerves. Enlarge- 

 ments on the trunks are known as ganglia. Nerves extending 

 from the chain ganglia are distributed among the viscera and the 

 walls of blood vessels. The regulation of the heart beat, the 

 secretion of digestive fluids, the contraction of the nonstriated 



Fig. 17. — Female reproductive system of Rana pipiens, ventral view, right 

 ovary removed. A, adrenal gland; B, bladder; Cl, cloaca; K, kidney; LI, large 

 intestine; O, oviduct; Os, ostium of oviduct; Ov, ovary; U, uterus; Ur, ureter. 



muscles in the walls of the alimentary tract, and other functional 

 activities of the viscera are controlled through the agency of the 

 sympathetic nervous system and the closely related parasym- 

 pathetic nervous system (Chap. IX). All of these activities are 

 involuntary and autonomic. The central nervous system, with 

 its peripheral connections, furnishes a mechanism for controlling 

 and coordinating bodily activities of all sorts (Fig. 16). 



Reproduction in the frog results from the fertilization of an 

 egg. The reproductive organs of the female consist of a pair 



