AUTHOR S ABSTRACT OF THIS PAPER ISSUED 

 BY THE BIBLIOGRAPHIC SERVICE, MARCH 31 



THE FATE OF HOMOZYGOUS YELLOW MICE 



WILLIAM B. KIRKHAM 



Oshorn Zoological Laboratory, Yale University 



TWO FIGURES 



INTRODUCTION 



The failure of breeders and investigators to obtain any homozy- 

 gous yellow mice and also the observed smaller average litters 

 born to yellow parents (Cuenot, '05; Castle and Little, '10) in- 

 dicated the advisability of attacking this problem from the 

 embryological side, a conclusion justified by the satisfactory 

 outcome shown below, A preliminary report on the present 

 research was made before the American Society of Zoologists 

 in 1916, published as an abstract in the Anatomical Record of 

 the following year. Since then Ibsen and Steigleder ('17) have 

 published the results from a somewhat similar piece of work, 

 but limited to embryos from females thirteen to nineteen days 

 pregnant; the details of this paper will be considered in connec- 

 tion with those of the present investigation. 



ANALYSIS OF THE PROBLEM 



White mice, and probably other mammals (compare Meyer, 

 '17), encounter two crises in their lives even before they are born, 

 the first occurring at the time of implantation in the wall of the 

 uterus, and the second at parturition. Loss of homozygous 

 yellow offspring at parturition would, if it took place, have been 

 observed by previous investigators, and their failure to record 

 either still births or moribund young as regular occurrences 

 after yellow matings is supported by the findings of the present 

 writer. There remained, therefore, the crisis at the time of 

 implantation as a likely key to the yellow-mouse problem. 



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