1180 



HORMONAL REGULATION 



de Groot, 1957), bulls (Hart, Mead and Re- 

 gan, 1946), chimpanzees (Yerkes, 1939; 

 Young and Orbison, 1944), and doubtless 

 many other species. Usually they cannot be 

 related to visible differences in the testes or 

 to the quantity and quality of the semen 

 (Lagerlof, 1954; Burrows and Titus, 1939; 

 Beach, 1940; Young, 1949; Craig, Casida 

 and Chapman, 1954; Wood-Gush and Os- 

 borne, 1956; Jakway and Young, 1958), al- 

 though Rasmussen ( 1952) reported an in- 

 verse relationship between fertility and 

 strength of sex drive in the rats he studied. 



Differences in behavior are not necessarily 

 related to the quantity of testicular hor- 

 mone, provided a certain minimum is pres- 

 ent. In an older study, examination of the 

 accessory reproductive organs by techniques 

 employed for hormone detection revealed 

 that tlie relatively inactive rats in a group 

 were actively secreting male hormone ( Hel- 

 ler, 1932). More recently it was found that 

 the behavioral differences in male guinea 

 pigs before castration continued to be dis- 

 played when the animals received equiv- 

 alent amounts of testosterone propionate 

 after castration (Grunt and Young, 1952b). 

 This lack of correlation between patterns 

 and the strength of mating behavior, and 

 levels of gonadal hormones is suggestive 

 with respect to the role of the hormones in 

 the expression of mating behavior and is 

 discussed elsewhere (p. 1199). 



The extent to wdiich mating behavior in 

 the male is dependent on testicular secre- 

 tions cannot easily be deduced from the ef- 

 fects of castration. Their variation from 

 species to species and from individual to in- 

 dividual of the same species is in fact so 

 great that it has done much to nurture the 

 doubt that gonadal hormones are the pri- 

 mary agents on which the sexual response 

 depends (Kinsey, Pomeroy, Martin and 

 Gebhard, 1953, p. 728 and elsewhere). The 

 impact of the book (and the earlier volume 

 on the male) on those not familiar with the 

 experimental studies was such that a fairly 

 detailed analysis of what has been found is 

 given. 



Courtship activity of the gobiid fish, 

 Bathygobius soporator, was not reduced by 

 castration, but the subjects became nondis- 

 criminatory and courted males and gravid 



and nongravid females in a like manner 

 (Tavolga, 1955). A castrated salmon parr 

 showed no interest in females (Jones and 

 King, 1952). Male Hemichromis bimacu- 

 latus, on the other hand, exhibited typical 

 movements of courtship and brooding for 

 202 days after castration (Noble and 

 Kumpf , 1936) . During this time at least one 

 male entered into as many as 13 successive 

 spawnings with a normal female. Other 

 males, castrated before the first spawning, 

 took part in at least 11 successive spawnings 

 in 146 days. At each spawning nuptial colors 

 and genital tubes developed. 



Male frogs castrated by Shapiro (1937a) 

 displayed no signs of sexual activation when 

 70 per cent of the control animals were mat- 

 ing. Steinach (1894, 1910), on the other 

 hand, reported that frogs displayed some de- 

 gree of sexual behavior months after cas- 

 tration. The same articles contain reports 

 of a diminished but nevertheless conscipu- 

 ous sexual activity in male rats as much as 

 a year after castration. The point may not 

 be important, but it is recorded for what it 

 is worth: the 1894 article, in which an in- 

 terest was expressed in clinical observations 

 on the sexual behavior of human castrates, 

 emphasizes the retention of sexual behavior 

 by castrates. The 1910 article, which seems 

 to have been written out of a background of 

 interest in the endocrine regulation of mating 

 behavior, emphasizes the loss of lil)ido fol- 

 lowing castration. 



The postcastrational behavior of several 

 species of birds has been described. Com- 

 plete castration of the pigeon did not pre- 

 vent entirely the development of copulatory 

 ability in all cases, but in others primary 

 sexual activity was abolished (Carpenter, 

 1933a). The frequency of billing was re- 

 duced by castration, but it was eliminated 

 in only 3 of 14 cases (Carpenter, 1933b). 

 His results are taken to demonstrate "that 

 the sexual hormones are of fundamental im- 

 portance in predisposing sexual activity." 

 Two of 16 gonadless pigeons "developed 

 complete and emphatic masculine behavior" 

 (Riddle, 1925) and he adds, "... it is clear, 

 that the thing which is usually accomplished 

 with the aid of the testis incretion may also 

 be accomplished without it." 



An incomplete and weak pattern of sex- 



