ANIMAL PRODUCTION. 765 



as long as the given system of breeding lasts, and it is possible to give a simple 

 formula in terms of n, the number of generations that the given system has 

 been followed, from which formula the proportions in generation n can be 

 directly computed. . . . 



" In most cases the constitution of the population changes from generation 

 to generation, giving a series of values not readily expressed in terms of n 

 (the number of generations) alone. In these cases diverse systems or diverse 

 parents give different series of values, almost all of w'hich are examples of 

 certain simply derived mathematical series or of their combinations. The 

 results are therefore best presented by giving first these fundamental series, 

 each with its designation. Then the results of any number of generations of 

 any system of breeding can be given by designation of the series which it 

 forms. 



"A systematic presentation of fornmlas [is given in the original paper] for 

 the proportions in any generation, resulting from any of the main types of 

 breeding, and with any of the common types of parental population, giving 82 

 numbered sets of formulas. In each case the limit approached is given, together 

 with the number of generations of breeding required to come within 1 per 

 cent of that limit." 



The influence of pituitary feeding upon growth and sexual development. — 

 An experimental study, E. Gof;tsch (BuL Johns Hopkins Hasp., 21 (1916), 

 No. 300, pp. 29-50, jjIs. 4).— The author found that "the dried powdered pitu- 

 itary extract, derived from both the anterior and posterior lobes of the gland, 

 when fed to young rats in excessive doses (0.1 gm. daily) causes failure to gain 

 in weight, loss of appetite, increased peristalsis, a mild enteritis, and certain 

 nervous manifestations, such as muscular tremors and weakness of the hind 

 limb. . . . Even when whole gland is fed over a short period of time, from 

 25 to 40 days, it causes a more rapid growth and development and gain in 

 weight, larger nipples in the female, and a coarser, drier, harsher growth of 

 hair than are seen in either control animals or after similar administration 

 of ovarian (corpus luteum) extract in equivalent dosage. 



" In comparison with the development in control animals, the ovaries, tubes, 

 and cornua of the uterus of animals fed with whole gland extract are larger, 

 more vascular, and cedematus in appearance, indicating increased development 

 and activity. . . . There is a generally increased vascularity produced in the 

 whole sexual system. The overdevelopment is apparent even in the muscle 

 coat of the uterus, which is considerably thickened, and is also more vascular. 

 . , . The testes show a considerably earlier growth and development; they 

 are completely and permanently descended at an earlier age, and their gross 

 weight is greater than in the control animal. This is evidenced by the ex- 

 tremely active spermatogenesis, with formation of spermatozoa, and by a 

 moderate increase in the amount of interstitial tissue, at a time when the 

 control animal is sexually still very immature. All these developmental, struc- 

 tural, and functional changes in the sex glands of both the male and the 

 female, produced by the feeding of pituitary extract, show an extremely selec- 

 tive and almost specific action of the latter upon the genital system. 



" The feeding of pituitary anterior lobe extract causes increased weight and 

 greater and more vigorous body growth and development over the control. 

 There is similarly an earlier and more active genital development. The fur 

 is harsher and thicker. Loss of weight, enteritis, and nervous manifestations 

 are not observed as in the beginning of whole gland feeding. . . . 



"After prolonged feeding of anterior lobe extract, over a period of 8 or 9 

 months, the sexual instincts are early awakened, along with the early maturity 

 of the sex glands. . . . The feeding of pituitary anterior lobe to parent rats 



