1186 



HORMONAL REGULATION 



tively small differences in androgen level 

 did not account for all the variance between 

 castrates (Beach and Fowler, 1959). 



To the extent that they exist, the dif- 

 ferences between the rat and guinea pig 

 could be one of species. A point is made of 

 this in a recent study in which a long ex- 

 perience with the response of individual 

 muscles and other tissues and organs of 

 male guinea pigs to testosterone propionate 

 is summarized (Kochakian and Cockrell, 

 1958). The stronger than normal responses 

 displayed by the rat, mouse, and hamster 

 are not encountered in the guinea pig. The 

 latter species apparently possesses some 

 mechanism or mechanisms to protect it from 

 large amounts of androgen. A correspond- 

 ing difference in the effect of testosterone 

 propionate on the sexual maturation of the 

 two species has also been noted (derail, 

 1958) . 



The efforts to restore noi'mal running ac- 

 tivity in castrated male rats have yielded 

 results unlike those obtained during efforts 

 to restore mating behavior. In 15 experi- 

 ments with castrated rats and in 3 with 

 senile rats, testis grafts and the injection of 

 macerated testicular tissue did not bring 

 about any significant improvement in ac- 

 tivity (Hoskins, 1925b). Bull testis extract 

 given during a 15-day period was without 

 consistent effect in 9 intact and 4 castrated 

 animals (Heller, 1932). Richter and Wis- 

 locki (1928), on the other hand, trans- 

 planted testes into the recti muscles and 

 wall of the scrotum and found that, when 

 the grafts became vascularized and "took," 

 an increase in activity occurred, but the in- 

 crease was much less than that seen by 

 Wang, Richter and Guttmacher (1925) fol- 

 lowing the transplantation of ovaries into 

 castrated males. The latter result appears 

 to be anomalous, but more recently quanti- 

 ties of testosterone propionate up to 25 mg. 

 did not increase the bodily activity of 9 

 senile males (Hoskins, Levene and Bevin, 

 1939), whereas estriol glucuronide and two 

 other estrogens fed to senile male rats 3 

 to 7 times a week for 3 to 5 weeks were 

 generally effective in augmenting activity 

 (Hoskins and Bevin, 1940). The suggestion 

 which comes from these studies is that run- 

 ning activity in the male is induced by estro- 



gens as it is in the female (Richter and 

 Hartman, 1934; Young and Fish, 1945). 



B. THE FEMALE 



As in the male, an understanding of the 

 relationship between the hormones and mat- 

 ing behavior depends on a knowledge of the 

 behavior. In fishes, and apparently in am- 

 l)hit)ians (Noble and Aronson, 1942), mating 

 behavior in the female is largely in the na- 

 ture of a passive response. Indicators of 

 receptivity are noted (Schlosberg, Duncan 

 and Daitch, 1949; Clark and Aronson, 1951 ; 

 Baerends, Brouwer and Waterbolk, 1955; 

 Morris, 1955b), but sharp end points have 

 not been described. Birds and mammals are 

 different. In the latter especially mating or 

 estrous behavior is well defined. It includes 

 some form of presentation or lordosis, fre- 

 cjuently a male-like mounting of other ani- 

 mals with or without copulatory thrusts, 

 and, especially in the rat, a great increase in 

 running activity. Although the point has not 

 been checked by comparable observations 

 of the two sexes, records of the display of 

 masculine sexual behavior by female mam- 

 mals give the impression that it is displayed 

 more commonly than is feminine behavior 

 by males (Beach, 1947). This is certainly 

 true in the guinea pig and a similar dif- 

 ference between the sexes has been noted 

 in fishes (Morris, 1955a). 



Not every species displays the three types 

 of estrous behavior. The rat and domestic 

 pig (Altmann, 1941 ) do so, but cyclic run- 

 ning activity as such has not been identified 

 in the guinea pig. It is probable, if our 

 knowledge of other species were more com- 

 plete, that an increase in general activity, if 

 not in running activity, would be found to 

 be associated with the mating period. The 

 restless, irritable, and explorative behavior 

 conspicuous in the estrous rhesus monkey 

 (Gari)enter, 1942a j is an example. 



In studies of the guinea pig and rat quan- 

 titative estimates of the duration of heat 

 have been made by recording the length of 

 time lordosis can be elicited in response to 

 fingering (Young, Dempsey, Hagquist and 

 Boling, 1937, 1939; Blandau, Boling and 

 Young, 1941). The average duration of the 

 single lordosis and the interval from the 

 first lordosis to the longest lordosis are re- 



