There is some reason to believe that a peculiar condition found in the majority of human albinoes, and known as nystagmus, is correlated with the absence of pigment in the central nervous system.
In complete human albinoes, albinism is correlated, in addition to nystagmus, with a peculiar roughness of the skin, making it harsh to the touch.
Like complete albinoes, this race suffers from photophobia, and is characterized by the albinotic facies.
The skins of albinoes gave no results Not only have such results been obtained with sponges, insects, cephalopods, birds and mammals, but Em.
And this leads to the inquiry as to whether albinoes ever exhibit evidence that they carry the pattern determinants in the absence of those for pigmentation.
For it is to be expected a priori that, since albinoes were derived from pigmented progenitors and may at any time appear, side by side with pigmented brothers, in a litter from pigmented parents, they would be carrying the pattern determinants of some one or other of their pigmented ancestors.
With regard to pattern, the evidence is now clear that albinoes may carry the determinants in both these ways.
With respect to albinoes carrying pattern as a visible somatic character, i.e.
But the author of this article has quite recently reared some albinoes in which the familiar shoulder hood and dorsal stripe of the piebald rat is perfectly obvious, in spite of the absence of the slightest pigmentation.
Thus these albinoes exhibit a pattern of pink skin similar in form with the black pattern of the piebald rat.
Moreover, some of the albinoes possess these particular "pattern" hairs all over the body and obviously such individuals are carrying the self pattern.
That these particular albinoes are carrying in the soma the pattern determinants simultaneously with the absence of some of the factors for pigmentation.
Not only do albinoes thus carry the determinants for pattern, but it has been known for some time that they also carry gametically, but never visible somatically, the determinants for either the ferment or the chromogen for one or more colours.
The experiments of the latter author show that, if a gametically pure black rat be crossed with an albino derived from a piebald black and white ancestry, all the offspring in successive litters will be black; but if the same black parent be crossed with albinoes extracted from parents of which one or both are grey, then both grey and black members will appear in the successive litters.
And when one of these albinoes is bred with a pure coloured individual, a mixed offspring will appear in the first generation.
But in such albino crosses the colour characters are latent because albinoes do not carry the whole of the complements for colour production.
Whether albinoes carry the tyrosinase or other ferment, or whether they carry the chromogen or chromogens, is not yet settled.
But that they never bear both is proved by the fact that, when albinoes are crossed with each other, none but albinoes ever result in the offspring.
Albino individuals may reappear among the offspring.
For there is expected in the offspring of this third son coloured individuals and albinoes in the proportion of 3: I.
The operation of Mendelian processes in human heredity is further shown by the close relationship that exists between the appearance of albinoes and cousin marriages.
A popular conception exists that albinoes are less constitutionally strong than the pigmented individuals of the same species.
But the question as to whether albinoes are more or less constitutionally vigorous than pigmented individuals of the same species may be tested by exact measurement.
Brodie, in ascertaining the physiological properties of nucleo-proteids, found that when they were intravascularly injected into pigmented rabbits, coagulation of the blood resulted, but of the eight albinoes which they used, none clotted.
And he found that all albinoes do not fail to clot when intravascularly injected with nucleoproteids.
When it was derived from albinoes no failures occurred.
The Himalayan rabbits reacted like complete albinoes, and 12% of them failed to clot when injected with nucleo-proteid extracted from pigmented animals.
The interesting fact was thus ascertained that all albinoes are not alike.
For, as the facts above described show, albinoes, though apparently identical externally, are yet the carriers of different hereditary characters.
This would give for albinoes and pigmented individuals the amount per kilogramme of body-weight required to kill in each case, and would afford a measurement of the relative resistance of the two races.
It was found that the resistance of albinoes towards the coagulative effects of injected nucleo-proteids was to that of pigmented individuals as.