64 



MORPHOLOGY OF THE VERTEBRATE BODY 



— b.n. 



functional units are arranged in such a manner that the anatomical 



divisions, as here in- 

 dicated, have only a 

 superficial significance. 

 Indeed, the sense-or- 

 gans, which receive the 

 external stimuH, and 

 the nervous system, 

 which transmits the im- 

 pulses from these sense- 

 organs to the muscles 

 that are thus called 

 into action, are all so 

 intimately related that 

 they may even be re- 

 garded as a single sys- 

 tem carrying out the 

 combined sensory- 

 neuro-muscular func- 

 tions of the body. Or 

 better, the term sensory- 

 neuro^muscular may be 

 used for the sense- 

 organs that receive the 

 stimuli, the nervous 

 system that transmits 

 and adjusts impulses, 

 and the muscles that 

 effect the forms of 

 bodily activity con- 

 trolled by the 

 nervous mechanism. 

 In like manner one 

 may speak of the 

 sensory- neuro -glandular 

 system. 



The nervous system 

 of the frog is a good 



Fig. 37. — Nervous system of frog from ventral 

 view, after Ecker. 



h.n., brachial nerve; 6r, brain; e, eye; f.t., filum ter- 

 minale; na, nasal sac; r.c, ramus cominunicans; s.c, 

 spinal cord; s.g., sympathetic ganglion; s.n., 1-10, spinal 

 nerves; s-;Tn, sympathetic trunk; va, vagus nerve. 

 (Redrawn from Wiedersheim, "Comparative Anatomy of PxamDlc of what exjsts 

 Vertebrates," copyright, 1907, by The Macmillan Co., 



printed by permission.) amoug Vertebrates m 



