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YEARBOOK, 1937 



squares numbered 9. The figure 1 in the middle square indicates that 

 all the progeny will be blended cross foxes. Now suppose these 

 blended cross foxes are bred together, as in the set of squares num- 

 bered 15. The figures in the squares indicate that every kind of fox 

 will result from these matings, and that in a large number of matings 

 the proportions may be expected to be 4 blended crosses, 2 Alaskan 

 red crosses, 2 smoky reds, 2 substandard blacks, 2 sub-Alaskan 

 blacks, 1 red, 1 standard black, 1 double black, 1 Alaskan black. If 

 an Alaskan black is mated with a smoky red, as in the set of squares 

 numbered 31, the result will be 1 Alaskan red cross to 1 blended cross. 

 If a sub-Alaskan black is mated with an Alaskan red cross, as in the 

 set of squares numbered 41, the result will be equal numbers of 

 Alaskan red crosses, blended crosses, Alaskan blacks, and sub-Alaskan 

 blacks. 



A SUGGESTED PROGRAM FOR FURTHER RESEARCH 



Fur farmers look to the scientist for leadership in the development 

 both of basic information in fur-animal breeding and of methods of 

 improvement, and they have appealed many times to the Federal and 

 State Governments for assistance. Little has been done, however, 

 by public agencies to develop this new and promising animal-produc- 

 tion enterprise, and there has been no systematic effort on the part of 

 State agricultural experiment stations or the Department of Agricul- 

 ture to develop, isolate, perpetuate, or record fur animals of superior 

 breeding ability. 



In order to place fur farming on a foundation comparable with that 

 of other branches of agricultural production, fundamental knowledge 

 is essential, and this can be obtained only by inaugurating a compre- 

 hensive program of research. Such a program might be conveniently 

 divided into three parts: 



1. Research work on reproductive cycles. Most of the study thus 

 far has been concerned with domestic species, and the available definite 

 information on wild animals is very meager, particularly as regards 

 species of economic importance. A more exact knowledge of the 

 reproductive cycles of North American fur animals could be applied 

 in several ways. It would be of great value — (a) in determining the 

 proper trapping seasons for restoring and conserving fur animals; (b) 

 in attempting intelligently to supplement the natural supply by restor- 

 ing and transplanting; (c) in insuring success in producing fur species in 

 captivity; and (d) in making possible a more efficient and economical 

 control of predatory and other injurious species. The object of 

 research on reproductive cycles would be to establish definitely — (a) 

 the breeding period of valuable fur animals; (b) the number of litters 

 and young produced yearly; (c) the type of embryonic development 

 (whether uninterrupted or with a delay in implantation); (d) the 

 hormone control of the breeding cycle; (e) the feasibility of artificial 

 insemination in those species that might be raised in captivity; and 

 (f) possibilities for producing or maintaining reproductive fertility by 

 hormone or other treatment. 



2. Breeding experiments with various fur animals under controlled 

 conditions. These should be conducted to study the inheritance of 

 prolificacy and fur quality, which includes color, sheen, and density. 



