40 ' • GENETICS [BoT. Absts., Vol. VIII, 



264. GowEN, John W. Studies in milk secretion. VIII. On the influence of age on milk 

 yield and butter-fat percentage as determined from the 365-day records of Holstein-Friesian 

 cattle. Maine Agric. E.xp. Sta. Bull. 293. 185-196. 1920.— Author gives results of study of 

 relation of age to milk yield and percentage of butter-fat, by which it is shown that yield of 

 milk rises at an ever- decreasing rate until the age of S\ years, and then declines at an ever- 

 increasing rate as age increases. Curves to fit the means of milk yield and butter-fat percent- 

 age are calculated. — E. Roberts. 



265. Graves, R. R. A study of Guernsey breeding. Hoard's Dairyman 59: 1068, 1069, 

 1072. 1 fig. 1920.— Guernsey sires (166) were divided into 3 classes on basis of sires of 

 production, sires of breeding daughters, and sires of breeding sons. These were traced back 

 to foundation sires and numbers noted. 68.7 per cent of sires were produced by out-crossing, 

 19.3 per cent by line breeding, and 12 per cent by inbreeding. An attempt is being made to 

 study inheritance of milk and fat. Relation of chromosome theory to facts observed in 

 breeding dairy cattle is pointed out. No case of complete prepotency for production either in 

 Guernsey or Holstein-Friesian breed was found. Variability in production of daughters, and 

 its relation to judging quality of sire is considered. — E. Roberts. 



266. Gross, K. Uber Vererbung von Augen- und Haarfarbe und den Zusammenhang 

 beider. [On inheritance of eye and hair color and the correlation between them.] Arch. 

 Rass.- u. Gesellschaftsbiol. 13: 164-170. 1920.— On the basis of a pedigree consisting of 4 

 grandparents, 5 each of the paternal and maternal fraternities, and 5 children the author 

 proposes an hypothesis to account (1) for a brown-eyed child from two blue-eyed parents 

 and (2) the association of blue eyes and brown hair and brown eyes and blonde hair as well 

 as the more usual associations. There are: P, a ground-factor for iris pigmentation; D, a 

 ground-factor for hair pigmentation; and F, an activating factor which affects pigment for- 

 mation both in iris and hair. The application of this hypothesis to the family in question 

 explains satisfactorily all of the observed combinations and distributions of eye and hair 

 coloration.— [See also Bot. Absts. 8, Entry 228.]— C. B. Davenport. 



267. GuYER, M. F., AND E. A. Smith. Experiments with typhoid agglutinins in rabbits. 

 [Abstract.] Anat. Rec. 20:214. 1921.— Experiments are being conducted to determine 

 whether immunization against germs of disease, practised generation after generation, will 

 eventually result in a truly hereditary immunity. Rabbits may readily be sensitized with 

 typhoid vaccine followed by the living bacteria so that their blood-serum diluted 320 to 640 

 times will agglutinate living typhoid bacilli. Females so sensitized may transmit to their 

 young and even to their grand-descendants the ability to agglutinate typhoid bacilli in- serum 

 diluted from 60 to 160 times.— After 2 or 3 months of development the young of sensitized 

 mothers are likely to show what appears to be a spontaneous rise of titre. If, for example, 

 they have been averaging a titre of 80 for some time, it may rise to 120 or even 160. After a 

 few weeks it drops back again. Rise of titre may be produced by the injection of milk into 

 the blood-stream.— Young from a sensitized mother, when nursed by a normal mother, retain 

 a fairly high titre for several months and may even show the spontaneous rise of titre men- 

 tioned. Young of a normal mother, when nursed by a sensitized mother, acquire a fairly high 

 titre, presumably from the milk of the foster-mother, but lose it rapidly after weaning time.— 

 M. F. Guyer and E. A. Smith. 



268. Hagem, Oscar. Einige Fa und Fe Generationen bei dem Bastard Medicago sativa X 

 M. falcata. [Some Fj" and Fe generations of the hybrid Medicago sativa X M. falcata.] Nyt 

 Mag. Naturvidenskab. 56: 149-165. 1919.— See Bot. Absts. 8, Entry 222. 



269. Hansen, W. Gedanken iiber Organisation und Arbeitsersparnis in der Pflanzen- 

 zucht. [Thoughts on organization and labor saving in plant breeding.] Deutsch. Landw. 

 Presse 1918: 261-262. 1918.— Author thinks that brief employment of young people does not 

 further breeding industry, that use of the professor as superintendent deprives leaders in gen- 

 eral of his knowledge which could be made available at breeding institutions, that the manag- 



