Full text: papers communicated to the first International Eugenics Congress held at the University of London, July 24th to 30th, 1912

V. G. Ruggeri.Biology and Eugenics.39 
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In order that a type be vital, i.e., be a biotype, it is necessary that it 
should have six different categories of determinants, but each category can 
be represented by any one of the determinants which are assigned to it. 
Thus, there may be theoretically 192 different combinations, genotypes, or 
forms of mouse having a special hereditary formula; as there might be just 
as many combinations for man, if also in him there were at disposition 15 
determinants, subdivided into six indispensable categories. The multiplicity 
of the human races is not, therefore, a zoological heresy. 
We have said that some of these determinants are dominant and others 
subject or latent, according to the doctrine established from the experiments 
of Mendel made since i860. This alternative is verified in crossings, when 
the two individuals which we wish to cross present two different determinants 
of one and the same category; so then in the descendants it is quickly seen 
which of the two determinants is the dominant one. For example, when 
we cross the grey mouse and the white mouse, all the offspring are absolutely 
of the same grey appearance; so we conclude that the determinant of the 
grey character is dominant over the white, since where there is dominance 
the first /law of Mendel is verified (1) that is, the uniformity of the F 
(according to Bateson's terminology), that is of the first bastard filiation. 
But the character of whiteness is latent in these grey mice of the first 
hybridisation; hence, while their progenitors were omozigotes, or pure types, 
they are in turn heterozygotes, their hereditary qualities are commingled of 
two alternative unities, which are the “ allelomorphs ” of Bateson(2), that is 
to say, of two opposed potentialities. Only one of these potentialities is 
visible externally, but the two determinants (like all the others of the 
hereditary formula) have passed into all the cells of their body, including 
the sexual cells, and these are separated the one from the other, which i9 
called disjunction or separation of the determinants, and constitutes the 
second law of Mendel which concerns F2, so that one half of the gametes 
(ova or sperm cells) receive the determinant of the character of greyness, and 
the other half the determinant of the character of whiteness, according to 
the hypothesis of the purity of the gametes. Thus, on crossing these grey 
(1) V. Haecker, Allgemeine Vererbungslehre, Braunschweig, 1911, p. 11. 
(2) W. Bateson, MendeVs Principles of Heredity, Cambridge, 1909.

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