ZOOLOGY AND BU'l'ANY, MICROSCOPY, ETC. 27 



in a shifting in a pins direction, -J. A¥liitc-spotting in rabbits— the 

 occnrrence of wholly nnpigmented areas in the skin and in the hair 

 thereon— occnrs in two forms, one recessive and the other dominant in 

 crosses witli the same race of unspotted ral)bits. Experiments point to 

 to the conclnsion that genetic variability by minnte gradations is a 

 reality, precisely as Darwin assnmed it to be, and this fact allows races 

 to be altered steadily and permanently by selection, either natiiral or 

 artiticial, as Darwin also assnmed to l)e the case. In short, nnit- 

 characters, while exhibiting Meiidelian inheritance, are often greatly 

 modified by crosses, and can be modified by selection alone, nnattended 

 by crossing. 3. lied eyes and yellow colonr in the common rat (3Ins 

 iiorvegiciis) are due to linked genes, and the same is true of pink eyes and 

 yellow colonr. The Hnkage between red-eyed yellow and albinism is 

 stronger still. On the chromosome theory the genes for albinism and for 

 red-eyed yellow are extremely close to each other in the same chromosome : 

 and the gene for pink-eyed yellow, while lying in the same chromosome, 

 is at some distance from the genes for albinism and red-eyed colour. 

 But this abstract hardly does more than indicate the general scope of 

 tlie paper. J. A. T. 



Female Reproductive Org-ans in some Falconidae. — Max Kollmaxn 

 {Bull. Soc. Zoiil. France, 11J19, 44, 4;:5-52, ?. figs.). About a hundred 

 cases are known where there is some development of gonads on the right 

 side of a bird. The frequent statement that there is no right ovary is 

 too sweeping. Kollmann has found six cases of a bilateral ovary and a 

 persistent right AVolffian duct in adult Falconidae {Accipetor nisus, Astur 

 pahtmbariiis, and Tin/iunculus tliniancuJux). AVhether the right ovary 

 may be functional or whether an ovum liberated from the right ovary 

 could reach the left oviduct remains uncertain, (/hapellier reports a 

 case of two oviducts as well as two ovaries in a duck, but tbis is extremelv 

 r:u-e. J. A. T. " 



Brachydactyly in Fowls.^C. H. Danforth {Amer. Journ. Anat., 

 lOr.t, 25, t»7-iir), 5 figs.). In certain strains of poultry (and pi'obably 

 in pigeons) there is a close correlation between brachydactyly (involving 

 the size and number of bones in the feet) and the presence of feathers 

 on the " tarsi." The evidence from the development shows that while 

 the size and number of skeletal elements are determined by the length 

 of the embryonic toe, there is no causal relation between toe length and 

 feathering. The data seem to indicate, on the contrary, that brachy- 

 dactyly, feathering of the tarsi, and probably syndactyly are all depen- 

 dent on one and the same factor. No attempt is made to postulate the 

 nature of this factor, but it is suggested that a study of the early func- 

 tioning of the endocrine glands in normal and abnormal embryos might 

 throw some light on the question. Xo correlation could be detected 

 between either of the characters referred to and polydactvly or comb 

 form. ■ J. A. T. 



A Hereditary Complex in the Domestic Fowl. — C, H. Danforth 

 {Genetics, 1919, 4, 587-96). Evidence is presented that brachydactyly, 



