4.-U) CAUSES OF THE VARIKTIES 



on liemp-seed only *. Horses fed on tlic fat marshy grounds 

 of Friesland grow to a large size ; while^ on stony soils of 

 dry heaths, they remain dwarfish. Oxen become very large 

 and fat in rich soils, but are distinguished by shortness of 

 legs ; while, in drier situations, their whole bulk is less, and 

 the limbs are stronger and more fleshy. The quantity of 

 food has great influence on the bulk and state of health of 

 the human subject ; but the quality seems to have less 

 power ; and neither produces any of those differences which 

 characterize races. 



In all the changes which are produced in the bodies of 

 animals by the action of external causes, the effect termi- 

 nates in the individual ; the offspring is not in the slightest 

 degree modified by them *, but is born with the original 

 properties and constitution of the parents, and a susceptibility 

 only of the same changes when exposed to the same causes. 

 The change in the colour of the liuman skin, from exposure 

 to sun and air, is obviously temporary ; for it is diminished 

 and even removed, when the causes no longer act. Tlie 

 discolouration, which we term tanning, or being sun-burnt, 

 as well as the spots called freckles, are most incidental to 

 fair skins, and disappear when the parts are covered, or no 

 longer exposed to the sun. The children of the husband- 

 man, or of the sailor whose countenance bears the marks of 

 other climes, are just as fair as those of the most delicate 

 and pale inhabitant of a city : nay, the Moors, who have 

 lived for ages under a burning sun, still have white children ; 

 and the offspring of Europeans in the Indies have the ori- 

 ginal tint of their progenitors. 



Blumenbach has been led into a mistake on this point 



» DerNaturforscher,T^i. 1. p. 1. pt- 9. p. 22. 



+ When the foetus in utero has stnall-pox or syphilis, there is actual com- 

 munication of disease by the fluids of the mother. This is a case altogether 

 different from those under consideration. Neither does hereditary predispo- 

 sition to particular diseases prove that acquired conditions are transmitted to 

 the offspring. There are natural varieties of organization, disposing different 

 individuals to different diseases on application of the same external causes. 

 These natural varieties, like those of form, and colour, and other obvious 

 properties, are continued to the children. 



