ANIMAL PRODUCTION. 475 



apparently pure breeds. In all cases the results agree closely with the Men- 

 delian hypothesis of sex-limited inheritance. 



" No cue familiar with good specimens of that breed could ever mistake a 

 barred Fi bird for a pure Rock. In certain of the F2 birds this is not the case. 

 Certain of the F2 matings produced birds which had a much finer, sharper and 

 cleaner cut barred pattern, or, to adopt a technical expression a ' snappier ' bar- 

 ring than any pure Barred Rock in the station stock. In other words, it ap- 

 pears that though the heterozygous nature of the Fi birds was apparent in 

 their external characters, the segregation of barred pattern in the F2 generation 

 was not merely perfect, but, to speak paradoxically, was more than perfect, 

 i. e., produced something better than existed in the parent stock. It may be 

 said, in passing, that the same thing is true with reference to comb tyiies. In 

 the Fi generation there were very few perfect pea combs, from the fancier's 

 standpoint. In the F- generation where pea combs segi'egated out relatively 

 many of them were of fine show room quality, and relatively few were badly 

 defective or intei'mediate between pea and single. . . . One further point 

 needs mentioning. In the Fi generation the male birds produced by the cross 

 of B.P.R. 5 XC.I.G. $ and its reciprocal were all alike in gametic formula 

 and external appearance. The F2 results indicate that the same results were 

 obtained with Fi males from the cross B.P.R. 5 XC.I.G. ? as with those ob- 

 tained from the cross C.I.G. 5 XB.P.R. $. These two kinds of males were, in 

 other words, equivalent in fact as well as in theory." 



On a modified Mendelian ratio among- yellow mice, W. E. Castle and C. C. 

 Little {Science, n. set:, 32 {1910), No. 833, pp. 868-870). — The authors present 

 evidence in support of the view that homozygous yellow mice do not occur, 

 because the yellow egg which by chance has met a yellow sperm has its career 

 ended thereby and is not, therefore, capable of fertilization by a nonyellow 

 spermatozoon. 



The authors crossed yellow mice inter se, and of 1,235 young produced 800 

 were yellow and 435 nonyellow, which is explained as being within the limits of 

 error. When mated inter se smaller litters were obtained than when yellows 

 were mated with nonyellows, there being in 1,805 young from those mated inter 

 se an average number per litter of 4.71, whereas in 325 litters obtained from 

 yellow mated with nonyellows the average number per litter was 5.57. This 

 difference is not so great as would be expected if homozygous yellow zygotes 

 perished without otherwise affecting the character of the litter, hence, the 

 authors conclude that the perishing of a pure yellow zygote makes iK)Ssible the 

 development of a certain number of other fertilized eggs. This may be either 

 by the liberation of more eggs normally at an ovulation than there are young 

 born subsequently, or the production of a relatively small number of young at 

 one birth may lead indirectly to more free ovulation subsequently. Selective 

 fertilization of the egg does not appear to occur in this case. 



These results, wherein a Mendelian class may be formed and afterwards lost 

 by failure to develop, seem to be comparable to those obtained by Baur with the 

 genus Antirrhinum in plants. 



The effect of one-sided ovariotomy on the sex of the offspring', L. Don- 

 caster and F. H. A. Marshall {Jour. Genetics, 1 {1910), No. 1, pp. 70-72). — 

 The right ovary and the greater part of the fallopian tube vi'ere removed from 

 a female albino rat and the same parts from the left side of another rat. Both 

 individuals gave birth to male and female offspring, which disproves the right 

 and left ovary theory of sex, at least in rats. 



Horns and antlers, Fambach {Ztsclir. Naturw., 81 {1909), No. 4, PP- 225- 

 26Jt, figs. 19). — ^A critical review of histological studies on the growing tissues of 

 horns and antlers. 



