Neither is this variation in the children from the colour of their parents improbable. The children of the blackest Africans are born white[088].  In this state they continue for about a month, when they change to a pale yellow.  In process of time they become brown.  Their skin still continues to increase in darkness with their age, till it becomes of a dirty, sallow black, and at length, after a certain period of years, glossy and shining.  Now, if climate has any influence on the mucous substance of the body, this variation in the children from the colour of their parents is an event, which must be reasonably expected:  for being born white, and not having equally powerful causes to act upon them in colder, as their parents had in the hotter climates which they left, it must necessarily follow, that the same affect cannot possibly be produced.

Hence also, if the hypothesis be admitted, may be deduced the reason, why even those children, who have been brought from their country at an early age into colder regions, have been observed[089] to be of a lighter colour than those who have remained at home till they arrived at a state of manhood.  For having undergone some of the changes which we mentioned to have attended their countrymen from infancy to a certain age, and having been taken away before the rest could be completed, these farther changes, which would have taken place had they remained at home, seem either to have been checked in their progress, or weakened in their degree, by a colder climate.

We come now to the second and opposite case; for a proof of which we shall appeal to the words of Dr. Mitchell[090], in the Philosophical Transactions.  “The Spaniards who have inhabited America under the torrid zone for any time, are become as dark coloured as our native Indians of Virginia, of which, I myself have been a witness; and were they not to intermarry with the Europeans, but lead the same rude and barbarous lives with the Indians, it is very probable that, in a succession of many generations, they would become as dark in complexion.”

To this instance we shall add one, which is mentioned by a late writer[091], who describing the African coast, and the European settlements there, has the following passage.  “There are several other small Portuguese settlements, and one of some note at Mitomba, a river in Sierra Leon.  The people here called Portuguese, are principally persons bred from a mixture of the first Portuguese discoverers with the natives, and now become, in their complexion and woolly quality of their hair, perfect negroes, retaining however a smattering of the Portuguese language.”