722 THE AMEBIC AN NATURALIST [Vol. XLIV 



lighter than, or at least not to exceed, that of the darker 

 parent. 



VI. The Origin and "Cause" of Albinism 



The question remains to be discussed: What is the 

 origin and "cause" of these albinos. The general con- 

 clusion seems justified, as in other mammals so in man, 

 albinism is due to the fortuitous union of two germ-cells 

 lacking this factor so that it is absent in the zygote 

 whence the albino proceeds. 



The objections to this view are three: (1) The usual 

 absence of any history of albinism in the family; (2) the 

 improbability of so frequent unions of two persons bear- 

 ing albinism recessive; (3) the lack of statistical accord 

 of the results of human breeding with those of animals. 



The first objection is not valid for any one who has 

 done experimental breeding, because he knows full well 

 how the recessive condition may be carried unexpressed 

 in the germ-cells for many generations awaiting that 

 chance conjugant that also carries the recessive condi- 

 tion. Absence of any history of albinism in a family has 

 the less significance in a country like ours where a large 

 proportion of the population can not tell the names of 

 their grandparents and know little of their cousins, who 

 may, indeed, live one to three thousand miles away. 



The improbability of so frequent unions of two or 

 three persons having albinism recessive has been re- 

 ferred to by Pearson. With a mathematical showing, 

 he tells the story of an albino who married successively 

 two pigmented (?) husbands and had some albino chil- 

 dren by each. "All three stocks, according to Mendelian 

 hypothesis, ought to have albinism in a recessive form. 

 You can calculate the chances against that because an 

 albino occurs in Italy about 1 in 30,000, in Norway, about 

 1 every 20,000 of the population, in Scotland, 1 in 24,000. 

 What are the chances that a woman of albinotic stock 

 should marry two stocks affected with albinism and not 

 related either to her or to each other?" The inference 



