HEREDITY IN MAN 



101 



FIG. 49. 



Pedigree of Brachydactylous family, slightly condensed from Drinkwater. 

 (Proc. Roy. Soc., Edinb., 1908.) 



$ Brachydactylous male. ? Brachydactylous female. 



$ Normal male. $ Normal female. 



Figures in circles represent so many normal individuals without discrimination 

 of sexes. 



A glance at the table will show that brachydactylous 

 persons (mated, as we have just seen, with normals) 

 produce both normal and brachydactylous offspring, 

 while normal individuals (also mated with normals) 

 produce only normal offspring. We therefore conclude 

 that the normal members of the pedigree produce nothing 

 but normal gametes, while the brachydactylous persons 

 produce both normal and brachydactylous gametes. In 

 short, the normals are comparable to the white fowls, 

 and the brachydactylous persons to the gray ones in 

 Fig. 48. The main difference between the two pedigrees 

 consists in the fact that the brachydactylous individuals 

 instead of being mated with their like, are mated with 



