Although, as has been stated above, this peculiarity occurs in individuals, who did not derive it from their parents, yet, like all those deviations from the ordinary structure of the body, which have been styled accidental varie ties, when once produced, it is disposed to propagate itself by hereditary descent. There are also certain individuals, who have a ten dency to produce it; so that even among the few European Albinos, of which we have a minute account, we have cases of its occurrence in two or more members of the same family, either as connected by parental descent, or by collateral We have no instance on record of the offspring of a male and female Albino.
The whiteness of the skin and hair, both general and partial, is not confined to the hu man race ; it is found in most, if not in all the species of the mammalia, and in some of these, as in the dog, the horse, and the rabbit, is the subject of daily observation ;t in most of them, however, the peculiar state of the eye does not exist. These white varieties, like other analogous cases among the lower animals, when once produced, are strictly hereditary, in which re spect they differ somewhat from the human Albino.
Various opinions have been entertained by physiologists respecting the nature of this pecu liarity, whether it should be considered as a morbid affection,I depending upon a diseased state of the constitution, and also respecting its immediate or efficient cause. The first of these points may be regarded as a verbal con troversy, depending altogether upon our defi nition of morbid action; but we conceive, that according to the ordinary definition of the term, we should not consider it as a disease, but as a connate deviation from the perfect structure of the animal frame, not produced by an external cause, and not removable by a remedial agent. For a correct knowledge of its physical cause, we are indebted, in the first instance, to an in genious conjecture of Blumenbach's, who ac counted for the red colour of the eye, and its extreme sensibility to light, by the absence of the pigmentum nigrum.§
This conjecture was shortly after verified by Buzzi of Milan, who took advantage of an opportunity which presented itself, of dissecting the eye of an Albino, in which the pigmentum nigrum could not be detected." He also ex amined the structure of the skin, which appeared to be deprived of the rete mucosum, that part of it in which its specific colour is supposed to reside ; the hair was also found to be deficient in its central coloured part.t Whether, in these cases, the pigmentum nigrum of the eye and the rete mucosum of the skin are absolutely deficient, or are only deprived of their colouring matter, so,as not to be detected by the eye, is a point on which different opinions have been formed by anatomists ;I perhaps, upon the whole, we may be induced to consider the lat ter opinion as the most probable.
What are the circumstances in the consti tution of the parents which should lead to this peculiarity in their offspring is entirely un known, nor have any conjectures been formed on the subject which can be considered as even plausible.§ The hypothesis of Buffon, which at one time obtained a considerable degree of credit, that white is, as it were, the primitive colour of nature, which, by various external causes, is changed to brown or black, but which the body has always a tendency to resume under favorable circumstances,11 is completely without foundation : nor does it appear that we can explain it upon the principle, that do mestication and the habits of civilized life have a tendency to produce a lighter shade of the complexion, because we trace no connexion between the supposed cause and the effect, and because the production of the Albino is complete in the first instance, and not brought about by any gradual or progressive alteration.
It appears that we must come to the con clusion, that although the anatomical or phy sical cause of the peculiarity is ascertained, yet that we are entirely ignorant of its remote cause, or of that train of circumstances which leads to its production.*