456 HOMEK WHEELON 



| 



prostatic atrophy and even to bring about a regeneration of lost func- 

 tion. 



Relation of the Testes to the Seminal Vesicles. Complete castration 

 during the period of rut prevents the seasonal development of the seminal 

 vesicles, or, if such development has already begun, arrests its further 

 progress. Unilateral castration, however, does not inhibit the growth of 

 the accessory genital glands and has no effect on the symmetrical arrange- 

 ment of these organs (Marshall). 



Accessory Glandular Structures Occurrence and Function. In 

 many animals there are accessory glandular structures, perinea!, inguinal 

 and preputal glands, which may be considered secondary sex characters 

 inasmuch as they serve as means of attraction between the sexes during the 

 mating season. These glands, as a rule, form secretions of a musky odor, 

 usually peculiar to the male, and often only during the rutting season. 



3. Influence of the Internal Secretion of the Testes upon Nervous 

 Structures and Their Functions. Those structural alterations and mani- 

 festations of new functions common at the period of puberty are closely 

 associated with manifestations of new emotional, psychic, and nervous 

 activity. The great structural alterations occurring at this period neces- 

 sarily throw new work upon the nervous system. The awkwardness of the 

 storm and stress period, also the psychic unrest, are probably due more to 

 bodily changes than to any very definite alterations in the nervous system 

 itself or its power to conduct impulses. Such structural changes associated 

 with the assumption of new functions by certain tissues results in a stream 

 of nervous impulses not previously experienced. The individual, because 

 of these conditions, is compelled to reinstate nervous equilibrium and 

 become accustomed to the stream of new impulses, that is, he must form 

 new "habits of acceptance," and establish new nervous reactions (Whee- 

 lon). At puberty inactive and dormant nerve centers acquire specific 

 sensibility. This is especially true in relation to the nervous mechanisms 

 concerned in the performance of the sexual act. The cerebral cortex is also 

 affected, as is evident by the appearance of sexual desire and changes of 

 disposition. 



Nervous Activity and the Breeding Season. During the breeding 

 season most animals demonstrate markedly increased vitality. Thus, the 

 bull fur-seal, at the beginning of the breeding season, is in a state of 

 perfect development and shows great nervous activity. At the end of this 

 time, on account of abstinence from food, the strain of battle and the 

 maintenance of the "harem," he becomes reduced to a state of extreme 

 emaciation. The migratory impulses of birds and the instincts of court- 

 ship, mating and caring for the young, are closely associated with the 

 periodic growth of the sexual organs. The antics, rapid flights, and dis- 

 play of feathers by birds may not be executed to attract the mate, never- 

 theless their appearance at this particular season indicates that the internal 



