ANIMAL PRODUCTION. 75 



for its purpose the improvement by selection of winter egg production in Barred 

 Plymoutla Rock fowls. Methods of breeding pursued (1) from 1898 to 1907, the 

 period of mass selection (E. S. R., 18, p. 471), and (2) from 1908 to 1912, the 

 period of progeny testing in which selection was made for low winter egg pro- 

 duction as well as for high production (E. S. R., 21, p. 271), have already been 

 noted. Since 1912 all selections for low and mediocre egg production have been 

 discontinued. 



Tabulated results of the 17-year selection period in which were involved 4,842 

 birds of which exact trap nest records were kept show that during the period of 

 mass selection the trend of mean winter production was downward with minor 

 fluctuations from year to year. Since 1907-08 there has been, with the exception 

 of two years, a gradual increase of mean winter egg production. The mean 

 winter production of all birds selected for high production from 1908 to 191.5 

 was 51.49 eggs and from 1908 to 1912 for all birds selected for low production 

 20.14 eggs. The mean winter production for whole flocks over the entire period 

 of the investigation was 35.05 eggs, which, in the opinion of the author sup- 

 ported by data presented, represents about the average winter production of 

 mixed flocks of this breed of fowls. 



The reason no effect was produced during the first ten years of selection and 

 the marked effect produced during the last seven years was, in the author's 

 opinion, because genotypically high producers were uniformly selected (in the 

 high lines) during the latter period and were not selected during the former 

 period. " By the introduction of the progeny test as an essential part of the 

 selection the whole process of the creation of a highly fecund race of hens was 

 transferred from the realm of blind chance to that of precise and definite con- 

 trol. ... To be effective in changing the average productiveness of a flock of 

 poultry selection we must pick out those birds as breeders which carry the 

 factors for high fecundity genetically, i. e., as an integral part of their hereditary 

 make-up, and not any other birds." 



The bearing of these results upon the general problem of the effectiveness of 

 selection in modifying germinal determiners is discussed. 



The effect of pituitary substance on tlie eg'g production of the domestic 

 fowl, L. N. Clark (Jour. Biol. Chem., 22 {1915), No. 3, pp. 485-49i).— Pituitary 

 substance was prepared from the brains of growing maumials and what 

 amounted to 20 mg. of fresh pituitary substance (anterior lobe) were adminis- 

 tered with the feed to each hen, per day, 690 hens being treated in this way. 



It was demonstrated that the feeding of this pituitary gland substance in- 

 creased the egg production of hens whose production curve was on the decline. 

 The dosage was effective on the fourth day after tlie first dose and lasted for 

 several days after the last dose. The hatchability of eggs from dosed parents 

 was increased. It is thought that positive results were obtained from the use 

 of the pituitary gland taken from gi'owing mammals, and negative results from 

 this substance taken from adults, which latter fact may account for the nega- 

 tive results of other investigators (E. S. R., 33, p. 472). 



Diuresis, the pituitary factor, D. Cow {Jour. Physiol., 49 {1915), No. 6, pp. 

 441-^51, figs. 8). — It was found that the increase in diuresis which follows 

 injection of extracts of duodenal mucous membrane is independent of the salt 

 content of such extracts, though such salt content may also produce an in- 

 creased flow of urine, is indirect, and is dependent on activity of the pituitary 

 body, which is stimulated by the injection of such extracts. The probable 

 sequence of events concerned in the production of diuresis is ingestion of fluid 

 by the mouth ; absorption of such fluid from the gastrointestinal tract ; and the 

 absorption by such fluid of some substance contained in tlie gastrointestinal 



