BIOLOGY. 371 



BIOLOGY. 



Castle, W. E., Harvard University, Cambridge, Massachusetts. Continua- 

 tion of experimental studies of heredity in small mammals. (For previous 

 reports see Year Books Nos. 3-19.) 



Progress has been made during the past year in the study of the 

 topics previously under investigation, particularly Imkage of charac- 

 ters in heredity and size inheritance. An intensive study is being 

 made of the interrelations of three linked genes in rats, and of possible 

 variations in linkage strength with age, environmental conditions, or 

 race. In the course of this investigation more than 30,000 young 

 rats liave been produced in the last year, but the data accumulated 

 have not as yet been studied carefully enough to warrant the formu- 

 lation of conclusions. Study is also in progress of the data on size 

 inheritance in rabbits, and this is nearly ready for publication. Linkage 

 relations of the genes of mice are also being investigated. In rabbits 

 a new linkage, between Angora goat and English color pattern, has 

 been discovered. The linkage previously reported, between English 

 pattern and dilution, with 38.5 ±5.34 per cent cross-overs observed 

 in the gametes of one individual, has not been confirmed in the case 

 of a second individual, w^here the two genes show" free assortment. 

 It seems probable, therefore, that the first case was based on an ''in- 

 sufficient sample" of cases, even though the deviation from equality 

 of cross-over and non-cross-over classes exceeded twace the probable 

 error. Evidence for the new linkage here reported for the first time 

 is much stronger, consisting of the progeny of three different sires, all 

 indicating linkage. 



Some new color varieties of rabbits, which are being advocated as 

 sources of fur supply, are also being investigated genetically. One 

 of these is the "Chinchilla," which proves to be an albino allelomorph, 

 similar to the silver agouti variety of guinea-pig. 



Four short papers have been published during the year. (See 

 bibliography.) 



Holmes, S. J., University of California, Berkeley, California. Completion 

 of a bibliography for use in a study of factors of evolution in man. 



The task of completing a bibliography on the "Factors of evolution 

 in man," for which a grant was made by the Carnegie Institution of 

 Washington, is nearly completed. During the past summer work was 

 carried on in the John Crerar Library of Chicago, the New York 

 Public Library, the Library of Congress, and the Surgeon General's 

 Library at Washington, and considerable aid w^as received from the 

 Eugenics Record Oflfice at Cold Spring Harbor, Long Island. The 

 funds remaining will be devoted to putting the references, now on 

 cards, in type-written form, so that parts of the bibliography, at least, 

 may be rendered available in the near future to workers in a restricted 

 number of localities. 



