GENETIC STRAINS AND STOCKS 85 



the amount of inbreeding is indicated by an inbreeding coefficient (F), devised by 

 Wright. 1447 



The use of the terms strain and substrain, again, are used according to the definitions 

 recommended by the Committee on Standardized Nomenclature for Inbred Strains of 

 Mice. However, some latitude has been exercised in this regard, for the term strain 

 has been used to designate those populations in the process of being inbred by brother x 

 sister, parent x offspring, or some other system of inbreeding. The term, stock, has 

 been used to designate those populations that are maintained for their identified genes 

 or identifiable genetic characteristics of genetic interest, with or without inbreeding. 



In the case of mice, only the established strains recently compiled by the Committee 

 on Standardized Nomenclature for Inbred Strains of Mice are included. Stocks 

 containing identified genes or identifiable genetic characteristics are numerous and 

 with a global distribution. The Roscoe B. Jackson Memorial Laboratory, Bar Harbor, 

 Maine, is probably the largest repository of murine genes in the world, and along with 

 this the laboratory has developed, and is continuing to develop, isogenic strains and 

 linkage stocks for testing purposes. Elsewhere in this volume, the linkage stocks at 

 this laboratory are discussed by Dr. Margaret C. Green. Material of this kind for 

 species other than mice is extremely limited. 



Similarly, no attempt was made to ascertain the number or kinds of inbred strains 

 in development for mice, whereas this information has been compiled for the other 

 species. It is strange that even though some of the earliest mammalian genetics was 

 done in such species as the rat, guinea pig, and rabbit, there is a paucity of such 

 material today. Fortunately there are indications of renewed interest in these species. 



As indicated above, information on the location and status of the various strains and 

 stocks came from previously printed lists, publications, and a questionnaire. From 

 these, arid my own knowledge of the whereabouts of strains and stocks, a mailing list 

 of more than a hundred names was compiled. At the present time similar surveys 

 are being made in Japan, Canada, Italy, and Germany. All the information obtained 

 has been arranged in a contributor-strain cross-file. This file will be kept active by 

 sending out periodic requests for bringing the status of strains and stocks up-to-date. 

 No information was solicited or obtained (except in a few cases) regarding the environ- 

 mental conditions under which the animals are maintained, the disease conditions 

 existing (unless of genetic significance), husbandry practices followed, nutritional 

 status, and so forth. It might be of considerable value for future listings to take into 

 consideration such exogenous factors, since certainly some genetic manifestations are 

 subject to environmental modifications. 



I. MICE 



As indicated above, only the established inbred strains of mice compiled by the 

 Committee on Standardized Nomenclature for Inbred Strains of Mice 219 and the list 

 of contributors are included in this section. The material is presented as published, 



