ANIMAL PRODUCTION. 773 



The following are some of the conclusions of the author: Mutation besins 

 with the production of a heterozygote. Inbreeding or self-fertilization is no 

 test for gametic purity. A cross of each individual with another variety is the 

 only method of being positively sure of the homozygous nature of a strain. 

 "When tlie heterozygote individual, produced by such a mutation, is a female, 

 or a hermaphrodite, and the absence of determinant couples with the determi- 

 nant for femaleness, the mutation can never show itself during all the normal 

 life of the group. ... It is possible for a character to be present, and yet 

 unab!e to manifest itself, because it only acts in modifying a second character, 

 and hence can not assert itself in the absence of this second character. Cuenot's 

 observations are explicable in this way." 



The author holds that all inheritance, including sex, is Meudelian. The in- 

 stances of so-called non-Mendelian inheritance or " blending " are cases where the 

 differences between the 2 forms were unknown. Secondary sex characters need 

 not be predetermined in the germ. The theory of gametic purity does not clash 

 with that of internal secretion. 



Selection index numbers and their use in breeding, R. Pearl and F. M. 

 Surface (Amer: Nat., J,,i {1909), No. 511, pi). 385-.'i00, fig.<i. ;2).— The authors 

 have devised a method of selecting breeding stock by which a selection of sev- 

 eral characters can be made at the same time in an impartial manner. 



A selection index number is a single mathematical function which combines 



several independent or correlative variables and also can be used as an adjunct 



to the score card for judging all kinds of animals. The formuhie are given 



which have been used for determining the index number for poultry and corn. 



5 (a+b) 

 The formula for the poultry selection index is as follows : Ii= — i ; — , In this, 



c+d+l 



Ii is the general or fundamental poultry selection index for an individual bird, a 

 the percentage of this bird's eggs which hatched, b the percentage of eggs actually 

 laid by this bird to the total number it was possible for her to lay between 

 February 1 and June 1 (that is, the breeding season) of the year for which 

 the index is calculated, c the percentage of her eggs which were infertile, and 

 d the percentage of chicks hatched from her eggs which died within 3 weeks 

 from the date of hatching. 



By the use of this formula an exact and impartial measure is substituted 

 for a rough and cumbersome expression of the relative effect of a number of 

 inherited characters. 



Yearbook of scientific and practical animal breeding' (JaJirb. Wiss. u. 

 Prakt. Ticrzucht, .', {1909), pi). CLXVII+ISS, pis. S).— This contains abstracts 

 of important investigations and the following papers: Animal and Plant 

 Breeding, by C. Fruwirth ; On the Size of Body and its Relation to the Size 

 and Development of the Lungs and Heart of Two Different Breeds of Sheep, by 

 A, Seeberger (noted on p. 776) ; The History of Castration in Man and Animals; 

 and Effect of Castration on the Animal Organism, by O. Worch. There are 

 also reports, noted below, on the pasturing of Pinzgauer cattle, by E. Groll, 

 and on jiasturing Bayreuth spotted cattle, by M. Miller. 



Pasture results for 1908 for the Alpine Societies in Upper Bavaria of the 

 Union for the Pure Breeding of the Pinzg'auer cattle, E. Groli. {Jalirb. Wiss. 

 u. I'mkt. Ticrzucht, // {1909), pp. XX.Vll~XLIV, pis. 8).— A report of results 

 in pasturing young cattle in 7 different pastures. Details of measurements 

 for each animal are given. The following table gives a summary of the aver- 

 age gains made in 6 of the pastures after discarding animals which were sick 

 or did not remain at pasture the full time : 



