190 



PHYSIOLOGIC GENETICS 



the environment is strongly implicated. An example of the former or genie role is the 

 fact that diabetics have a sixfold increase in alpha-2-serum proteins whereas hybrids, 

 stemming from two or four diabetic parents from different inbred families, exhibit 

 low or normal levels of this diagnostic protein. 494 



Dr. Degenhardt: Is there any information about a preferred time for genie 

 interaction in early embryonic development ? I am thinking only of Polydactyly. 



Dr. Wright: Dr. Scott worked out the embryology of the polydactylous monster. 

 About the seventeenth or eighteenth day he found broad, paddle-shaped limb buds 

 and that the hindbrain was growing too much for the rest of the body, causing it to 

 bulge out through the top of the head. Probably action of the gene occurred much 

 earlier than that. 



Dr. Degenhardt: We found in our investigations on the effect of irradiation 

 early in embryonic development that there is a critical stage for inducing Polydactyly 

 in the inbred strain C57BL/KsJ, in which polydactyly normally appeared at a 2.2 per 

 cent rate, between day seven to day ten of gestation (table 44) . The table illustrates 



Table 44 

 Incidence of polydactylism in controls and after X irradiation (130 r) at 



SUCCESSIVE STAGES OF EARLY GESTATION IN MICE OF THE INBRED STRAIN C57BL/KsJ 



Li = Litter 

 NB = Newborn 

 = Average litter size 

 ENB = Examined newborn 

 t = Incidence of 7 toes 

 X = One case of postaxial polydactylism 



the incidence rate up to 27.2 per cent, and it may be possible that this is the threshold 

 of genie interaction. But there seems to be another critical phase. This work has 

 been done by Dr. Charles P. Dagg. 236 He gave 5-fluorouracil at a certain stage of 



