V. G. Ruggeri.Biology and Eugenics.41
if we consider that this can also happen amongst distantly related cousins,
who are naturally ignorant of their relationship.
The recessive character of albinism and obedience to the Mendelian law
seem, then, well established, in spite of the mathematical criticisms of
Pearson, which we pass over, as the same Davenports have replied to them.
Without wishing to enter into particulars special mention should,
however, be made of a family of mulattos of Louisiana with partial
hereditary albinism, which has been studied in Italy by Frassetto and Levi(i).
The genealogical tree shows various generations, each of which presented
one albino parent. But one of these generations is specially interesting for
the large number of children born to one couple, viz., 15, of whom eight
were albinos: the percentage of albinism is very nearly 50 per cent., as was
foreseen from the theory, admitting that the normally pigmented parent had
had the character of albinism as a recessive, according to the formula
(dr x r r), in which d = dominant, r = reoessive or remissive. In the next
generation the descendants are still few (and also their number varies
according to the two authorities), and their behaviour would make it
difficult—if it were not too soon to draw conclusions—to deny that they
confirm the Mendelian law.
On the other hand, if the normally pigmented parent does not possess the
character of albinism as a recessive the behaviour is different—i.e., in the
first generation none of the children ought to show evident albinism. The
case of Farabee(2) isi much to the point. An albino negro wedded to a negress
had three normally pigmented children. But the latent albinism showed
itself in the second generation exactly as we have seen for the albino mice.
Since one of the three sons had 15 children of two negresses, of whom four
were albinos, which corresponds precisely to the division of the determinants,
the isolated recessive character remaining and hence being evident in the four
children. This behaviour shows that even in the second generation the
character of albinism was recessive in only one of the two parents ; otherwise
the proportion would have been 50 per cent, as in the case Frassetto-Levi.
Clearly families with few children afford much less demonstration.
As a general rule when a generation is passed over, as in the case referred
to, it may be said that the character is recessive. It would seem that red
hair is in a similar case, since Frédéric refers to a southern German with red
hair, who had two sisters with brown hair, both the parents also had brown
hair, while one grandmother had red hair.
Nevertheless, Frédéric, with much caution, leaves the question of
Mendelism in suspense, whether as regards red hair or albinism, although
(1) E. Levi, Albinismo parziale eredo-famigliare in Negri della Luisiana. Arch, per
l’Antrop. e l’Etnol XXXIX. (1909), fase. 1 ; F. Frassetto, Casi di albinismo parziale eredi-
tario nella famiglia Anderson della Luisiana. Atti Soc. Rom. di Antrop. XV. (1910), fasc. 2.
(2) W. C. Farabee, Notes on a Negro Albinism. Science, New Series, XVII. (iqcu). Jan.-June.
