728 THE AMERICAN NATURALIST [Vol. XLIV 



3. The proportion of albinos in any family probably 

 accords in the long run with Mendelian expectation, as 

 in other mammals. From two non-albinic parents the 

 proportion for families of four or more children is 34 

 per cent, albinos instead of the expected 25 per cent. 

 But various causes result in an omission of normal in- 

 dividuals and tend to swell the proportion of the abnor- 

 mal. When one parent is albinic and albino offspring 

 occur at all we get (Rid and 4 cases in P. W.), a total of 

 16 albinos and 15 pigmented, which accords with expec- 

 tation. 



Cold Spring Harbor, N. Y., 

 September 8, 1910. 



F. LITERATURE CITED 

 Agassiz, L. and E. C. A Journey in Brazil. 540 pp., Boston [The 



Bateson, W. In: Heredity and Disease. Proc. Royal Soc. of Medicine, 

 II [pp. 22-30 of reprint]. 



Davenport, G. C. and C. B. Heredity of Hair Color in Man. Ameri- 

 can Naturalist, XLIII, 193-211, April. 



Ehrmann, S. Das m<>him>tisch<> lament und die pigmentbildenen 

 Zellen des Menschen und der Wirbelthiere in ihrer Entwickelung 

 nehst Bemerkungen iiber Blutbildung und Haarwechsel. Bibliotheca 

 medica Abth D", Hft. 6, 80 pp., 12 Taf. 



Lagleyze. L'oeil des albinos. Arch, d'ophthalmologie, XXVII, 

 p. 280. 



Pearson, K. Note on the Skin Color of the Crosses between Negro 

 and White. Biomctrika, VI, 348-353, PI. 1, March. 



Pearson, K. In : Heredity and Disease. Proc. Eoyal Soc. of Medicine, 

 II, pp. 54-60. 



Young, H. B. Illinois Medical Journal, XII, 201. 



