202 



MENDELISM 



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pO — '^o^ 



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■CH 



0+ pi 



^ 



'•* 

 f» 

 o 



o 



o- 



*o 



r*0 



■CK- 



2i,-L<to 





o — 0+ 



■<X3 



rO+ 



LiS« — ♦+ 



behaves as a simple 

 dominant to the normal 

 form, z.e. that it depends 

 upon a factor which the 

 normal does not con- 

 tain. The recessive nor- 

 mals cannot transmit the 

 affected condition what- 

 ever their ancestry. 

 Once free they are always 

 - free, and can marry other 

 normals with- full confi- 

 dence that none of their 

 children will show the 

 deformity. 



The evidence avail- 

 able from pedigrees has 

 revealed the simplest 

 form of Mendelian in- 

 heritance in several 

 human defects and dis- 

 eases, among which may 

 be mentioned presenile, 

 cataract of the eyes, an 

 abnormal form of _skin 

 thickening in the palms 

 of the hands and soles of 

 the feet, known as tylosis, 

 and epidermolysis buly 

 losa, a disease in which 

 the skin rises up into 

 numerous bursting 

 blisters. 



