ANIMAL PRODUCTION. 571 



recorded. In 51 cases both were ewes and 4 ewes out of 37 were sterile. In 

 93 twins of unlilce sex 5 out of 36 ewes were sterile. The breeding of the other 

 ewes could not be traced. 



These figures indicate that a " free-mai-tin " is more likely to occur in cattle 

 than in sheep whenever the twins are of unlike sex. 



History of Hereford cattle, J. Macdonald and J. Sinclair (London, 1909, 

 rev. ed., pp. XVI-\-501, pis. 31). — A new edition of this well-known work, first 

 published in 1886, revised and enlarged to include an account of the recent 

 development of the breed. 



The draft horse, P. de Choin (Ann. In^t. Nat. Agron., 2. ser., 8 (1909), No. 

 2, pp. 275-310, figs. 4). — It is pointed out that the methods now in use for judg- 

 ing draft horses are crude. A more extensive use of the dynamometer is 

 recommended. The topics treated in a discussion on the utilization of the 

 motive power of the horse to better advantage are road building, methods of 

 harnessing, driving, and the construction of vehicles. 



Report on the stock show at Prek-Po, Baudoin (liul. Econ. Indo-Chine, n. 

 scr., 12 (1909), No. 80, pp. -'i51-.'t73, figs. 11). — This contains an account of the 

 live stock industry in Cambodia, French Indo-China. Descriptions and 

 measurements are given of zebus, bulfaloes, and horses exhibited at the annual 

 fair. 



Data on certain factors influencing the fertility and hatching of eggs, 

 II. Pearl and F. M. Surface (Maine .S7«. Bui. 168, pp. lO.'i-lGJi, dgnis. 2). — This 

 bulletin presents data to show that fertility of the hen's egg and its ability to 

 hatch are two essentially different things, and also reports a quantitative study 

 of the relationship between these two properties and their inheritance in th6 

 offspring. 



The correlation between fertility and hatching quality was numerically deter- 

 mined for 2 seasons. " So far as the present data indicate there is a small 

 but still sensil)lo correlation between the fertility and hatching quality of eggs. 

 'Iliis means that in general or on the average the hen whose eggs run high in 

 fortility will also tend to show a high hatching quality of eggs (percentage of 

 fertile eggs hatched) and vice versa." 



The mean or average percentage of infertile eggs, as shown in the breeding 

 records of the 1008 group of birds, was 21.71. This high percentage is explained 

 because of the unsuitable housing conditions. In 1000 the average percentage 

 of infertility, taking all the birds of the year together (the returns on .5,000 to 

 6,000 incubated eggs), was 14.14. If the early portion of the breeding season 

 had been left out of account, the average percentage of infertility would have 

 been considerably reduced. 



The average percentage of fertile eggs hatched in the 1908 season was 37.24, - 

 and in 1909 50.68. The degree of absolute variability as measured by the 

 standard deviation in all but one case was somewhat greater in the case of 

 hatching quality than in the case of fertility. While hatching quality aj^peared 

 to be a slightly more variable character than fertility, the opposite was the case 

 if the degree of variation in proportion to the mean is considered. Both the 

 fertility and hatching quality were much better when the breeding was done in 

 a curtain-front house. 



" It is shown that the individuality of the female bird is a very important 

 factor in the determination of the fertility of eggs. Different individual females 

 have characteristic degrees of fertilitv of their eggs, independent (within limits) 

 of the character of the male bird with which they are mated. This fact empha- 

 sizes the importance to the breeder of trapnesting through the breeding season 

 at least." 



35128— No. 6—10 a 



