19191 DAIRY FARMING DAIRYING. 473 



of the sterility in the hybrids. This is the final stage in spermatogenesis, for 

 divisions of the primary spermatocytes do not occur nor is there any trace of 

 abnormal mitoses." 



Partial self-fertilization contrasted with brother and sister mating, R.. B. 

 RoBBiNs (Jour. Genetics, 7 (1918), No. 3, pp. 109-202). — If a fixed proportion of 

 the individuals of each generation of an ideal population reproduce by self- 

 fertilization and the remainder by random pairing, and if only a single typical 

 Mendelian character is considered with respect to its distribution in successive 

 generations, the author finds by the use of algebraic methods that heterozygotes 

 can never entirely disappear and that the proportion present steadily approaches 

 a definite limit different from zero. The claim of Bruce (E. S. R., 37, p. 769) 

 that this mixed type of reproduction would give results essentially similar 

 to brother and sister mating is thus disproved, for in a previous communication 

 (E. S. R., 38, p. 367) the author shows that in continued brother and sister 

 mating the heterozygotes do tend to disappear. 



On the nature of size factors, S. Wright {Genetics, 3 (1918), No. 4, pp. 

 367-374)- — The author announces a theorem in the calculus of correlation 

 whereby the observed correlation between two structures or organs of the body 

 can be expressed as a function of those fi-actions of the variation in each of 

 the characters which result from the same " causes." By making certain 

 simplifying assumptions, it is thus possible to estimate the relative influence 

 of those hereditary size factors which affect the animal body as a whole and 

 those which affect only a particular part. 



The method is applied to data published by MacDowell (E. S. R., 32, p. 

 573) on the length and widtli of skull and the lengths of humerus, femur, and 

 tibia in rabbits. It was found that general body factors could be assigned from 

 62 to 75.5 per cent of the influences which determine the magnitude of the 

 individual dimensions, that 6.6 to 31.5 per cent resulted from factors operating 

 on a particular dimension and not on any of the others, while the remainder 

 could be attributed to causes acting on more or less independent groups of 

 bones. The skull bones form one such group and the leg bones another. The 

 femur and tibia also form a subgroup subject to certain influences not affect- 

 ing the humerus, while the femur and humerus, which are homologous bones, 

 are influenced by another set of factors independently of the tibia. 



' DAIRY FARMING— DAIRYING. 



Dairying with purchased feeds only, F. W. Woll (Hoard's Dairyman, 58 

 (1919), No. 1, pp. 5-7, figs. 9).^-This is an account of a profitable dairy herd 

 where 330 Holstein cows receive only purchased feeds. It is operated by a 

 creamery company near Los Angeles, Cal., on land worth over $500 per 

 acre. Low producers are speedily discarded and the cows in the herd average 

 about 1 lb. of butter fat daily per head. Four per cent, grade A, milk 

 is sold for $4 per hundredweight. The concentrates fed to all animals are 

 coconut meal, wheat bran, and dried beet pulp, while cows that are milked 

 three times daily receive in addition rolled oats and bran. A relatively high 

 liroportion of concentrates is fed, a profitable practice with high producers 

 when alfalfa hay is $22 a ton. Corn for silage is contracted for at $3.50 a 

 ton, but charges for hauling and labor add $1..50 or more to the cost. Con- 

 sidei'able income is derived from the sale of manure and young stock. 



Factory butter, cheese, and condensed milk production during the war, 

 T. R. PiRTLE (Hoard's Dairymnn, 57 (1919), No. 20, p. 1000, fig. i).— Data from 

 the census of 1909, the manufacturing census of 1914, and the reports issued 

 by the Bureau of Markets of the United States Department of Agriculture on 



