776 EXPERIMENT STATION RECORD. [Vol.38 



dual fowls for the purpose of discarding those heterozygous for the character in 

 question. 



Poultry culture (Mass. Bd. Agr. Bui. 1, 5. ed. rev. {1917), pp. 159, pis. 14, 

 figs. 6). — This is the fifth edition, revised, of this treatise on the different 

 phases of poultry culture in Massachusetts. A bibliography is appended and 

 the bulletin indexed. 



Poultry raising in Colorado, W. E. Vaplon et al. {Denver, Colo.: State 

 Bd. Immigr., [1917], pp. 16, fig. 1). — ^A series of articles on poultry raising 

 written by men of practical experience in the State for the information of 

 prospective settlers. 



Pets: Their history and care, L. S. Ckandaxl {New York: Henry Holt and 

 Co., 1017, pp. XII +372, pis. 32). — This work, which closely follows the title, 

 was written by the assistant curator of birds, New York Zoological Park. It 

 treats of mammals, birds, reptiles, and fishes that are or may be reared as pets. 



Color inheritance in mammals. — II— V, S. Wrighi {Jour. Heredity, 8 

 {1917), Nos. 8, pp. 373-378; 9, pp. 426-430; 10, pp. 473-475, 47&-480).—Fo\it 

 papers are presented. 



II. The mouse. — In this paper a detailed analysis is given of the present state 

 of knowledge of color inheritance in the mouse. A list is given of the seven 

 sets of MendeUan allelomorphs that have been identified and of the three series 

 of color variations that so far have been analyzed. These are classified ac- 

 cording to their apparent physiological effects under the scheme already noted 

 (E. S. R, 37, p. 866). 



III. The rat. — This digest of data on the inheritance of color in rats consists 

 in the main of an interpretation of the results of Castle's selection experiments 

 with hooded rats (E. S. R., 27, p. 369). 



The author concludes that genetic variations are occurring sufficiently often 

 to give a basis for selection to an indefinite extent. " Under any interpretation. 

 Castle's selection experiment demonstrates the efficacy of Darwinian selection. 

 It is true that one large mutation occurred with effects perhaps as large by 

 itself as the entire plus selection series, but where such a variation gives one 

 new level selection has produced a continuous series of stable levels. This 

 would give selection of small variations a more important place in evolution 

 and animal husbandry, where it is nice adjustments of one character to another 

 or to the environment that count." 



IV. The rabbit. — The author lists the ten unit differences known to be in- 

 volved in the inheritance of color in rabbits. These are classified into seven 

 independent sets of allelomorphs, three of which have been proved to be triple 

 allelomorphs. These three sets of allelomorphs, as in the case of several other 

 mammals, determine linear series of physiological effects not to be explained as 

 linkage of factors in the germ cells. 



V. The guinea pig. — In this brief discussion it is noted that " coat pattern 

 in guinea pigs, and doubtless other animals as well, must be determined by a 

 complex of causes of very diverse kinds. There are hereditary factors of various 

 sorts and factors which are of the nature of accidents in development. There 

 are factors which affect the extent of pattern and others which determine its 

 localization. Of the latter some relate the pattern to the axis of symmetry and 

 organs of the body, while others are random in their incidence. Some factors 

 affect only the tortoise pattern in one way or another, or only the piebald pat- 

 tern, while others have a simultaneous influence on both. The result is such a 

 diversity of pattern among tricolors that a rough sketch will identify almost any 

 animal in a stock of a thousand." 



