generation rooted to their native soil. The large numbers of persons who are found in this valley having the same surnames is a proof of the well-known fact that there is little or no emigration from the valley, and that there is an indefinite amount of intermarriage between the natives. It is conjectured that the continuance of these conditions through a long period has rendered the population more or less consanguineous, and that we see in crétinism an example, upon a large scale, of the evil effects of alliances of kindred.
This explanation commends itself by reason of its general applicability to crétinism. The disease is commonly found in valleys, on islands,[1] or in other circumscribed areas, in which circulation is restricted, or the inhabitants are non-migratory; and it is rare on plains, where communications are free. It will at once be asked, "Why, then, are not the tributary valleys of the valley of Aosta full of crétins?" The answer is, that these lateral valleys are comparatively sterile, and are unable to support their population from their internal resources. Large numbers annually leave, and do not return,—some come back, having formed alliances elsewhere. There is a constant circulation and introduction of new blood. I am not aware that there are returns to show the extent to which this goes on, but the fact is notorious.[2]
- ↑ Dr. Blackie gives the remarkable instance of "the island of Medworth (Niederworth?), near Coblence, where the inhabitants hold no connection with those on shore, and consequently intermarry constantly with one another." This island, according to Dr. Blackie, had no less than 40 crétins out of a population of 750.
- ↑ The case of the Val Sesia is not strictly in point, since it is not a tributary of the Val d'Aoste, but it may be quoted to show the extent to which this migration goes on. Mr. King says, "The population of the whole Val Sesia being estimated at 35,000, it is evidently utterly unable to maintain a tithe of that number from its own resources. The necessary result is, a regular periodical migration of all the able-bodied and active males, for varying lengths of time, into different parts of Europe.... A large number of the towns of Italy and France, as Genoa, Milan, Turin, and even Paris, are supplied with an immense influx of skilled labourers and artificers from these Vals. Some idea of the extent of this migration may be formed from the fact, that 8000 Val Sesians leave their homes annually, many of them for years."—Italian Valleys of the Alps, p. 373.
