PHYSIOLOGY, CHEMISTRY AND PATHOLOGY 457 



impulses to exertion are dependent upon the active phase of the sexual 

 cycle. Stags are in a state of constant sexual excitement during the rutting 

 period and fight one another for the possession of the hinds. At the 

 termination of the season the sexual excitement and fighting ceases and 

 the stags once more herd together peaceably and apart from the females, 

 the antlers are shed and the sexual cycle enters upon its quiescent phase. 

 The functioning of scent glands is also closely associated with the cyclic 

 increase in nervous activity. Although these glands are present through- 

 out the year, the stimulus to activity apparently is wanting save during 

 the breeding season. 



In cold-blooded anhnals there is a periodicity in the occurrence of 

 reflex responses. Thus in the heart of frogs, newts, salamanders and eels 

 vagus inhibition is markedly diminished or absent at times roughly corre^ 

 sponding to the periods of sexual activity (McLean). The male frog, im- 

 mediately following hibernation and at a time of great emaciation and 

 poor reflex coordination, demonstrates a perfect "embracing reflex." This 

 reflex, maintained throughout the spawning season, is responsible for the 

 posture during the act of copulation. It is elicited by stimuli applied to 

 the skin of the chest and is restricted to a small group of muscles in the 

 fore limbs. The embracing reflex is entirely spinal, as may be shown by 

 stimulation of the chest skin of the isolated segment of the fore limbs. 

 Removal of the testes of the frog results in the loss of reflex sensibility 

 and failure of development of certain secondary characters of sex during 

 the breeding season. Testicular transplants in such frogs are sufficient to 

 establish these seasonal changes, hence the testicular substance either acts 

 directly upon the nerves or upon the muscles supplied by certain of them. 

 Section of the nerves in one fore-arm of the frog prevents seasonal changes 

 in that arm; however, the normal arm develops characteristically. Such 

 observations led Nussbaum to the belief that the castration of the gonads 

 stimulates only certain nerve structures. The error of this conclusion was 

 soon shown to lie in the arrest of motility and sensibility of denervated 

 parts (Pfliiger). In spite of this criticism, such observations are of 

 special interest because they indicate that the development of certain sea- 

 sonal changes are dependent not only upon the elaboration of an internal 

 secretion by the testes, but also upon the presence of a normally function- 

 ing nervous apparatus. 



DispositionaZ Characteristics and the Testes. The quiet and rather 

 phlegmatic temperament of castrated individuals is characteristic. 

 It is reported that the eunuchs of Constantinople are avaricious, illogical, 

 obstinate, possess little judgment and accept information without 

 proof. As a rule, they are fond of children and animals and are faithful 

 in their affections, but possess little courage (Hikmet and Regnault). 

 Their mentality is often deficient and they are very fanatical. Eunuchs 

 ,of high intellectual ability, however, are not uncommon. The re- 



