39§ 
tooth corn,’ in which the tooth nearly disappeared even in the second 
generation. A third race, the ‘ chicken-corn,’ did not undergo so 
great a change, but the seeds became less polished and pellucid.”— 
{The Variation, vol. i., p. 322.) 
“The modern experiments of Van Mons and of de Vilmorin have 
instructed us as to the number of generations and of years necessary 
to raise certain fruit trees, &c., from the wild state to that of culti 
vated trees fit for food. Three generations, according to Vilmorin, 
suffice for the carrot ; three generations, which comprise fifteen years, 
suffice, according to Van Mons, for stone fruit trees—peaches, apri 
cots, plums, cherries.”—(Prosper Lucas. Traité Philosophique et 
Physiologique de VHérédité Naturelle, vol. ii., p. 472.) 
“Wiseman assures us on good authority that in the United States 
those slaves who for three generations have lived in domestic service, 
have the nose less depressed (déprimé), the lips less protruding, and 
the part of the head covered by the hair longer in each generation, 
while the slaves which work in the fields lose scarcely any of their 
original conformation.”—(Prosper Lucas. Ibid. vol. ii., p. 464.) 
Humboldt remarks that— 
“ White men born in the torrid zone walk barefoot with impunity in 
the same apartment where a European, recently landed, is exposed to 
the attacks of the Pulexpenetrans. This insect, the too well-known 
chigoe, must therefore be able to distinguish what the most delicate 
chemical analysis fails to distinguish, viz., a difference between the 
blood or tissues of a European and those of a white man born in the 
country. But the discernment of the chigoe is not so surprising as it 
at first appears, for, according to Liebig, the blood of men with 
different complexions, though inhabiting the same country, emits 
a different odour.”—( The Variation, vol. ii.,pp. 275-6.) 
“Some of our countrymen engaged, about the year 1825, in con 
ducting one of the principal mining associations in Mexico, that of 
Real del Monte, carried out with them some English greyhounds 
of the best breed, to hunt the hares which abound in that country. 
The great platform which is here the scene of sport is at an elevation 
of about 9,000 feet above the level of the sea, and the mercury in the 
barometer stands habitually at the height of about 19 inches. It was 
found that the greyhounds could not support the fatigues of a long 
chase in this attenuated atmosphere, and before they could come up 
with their prey, they lay down gasping for breath ; but these same 
animals have produced whelps which have grown up, and are not in 
the least degree incommoded by the want of density in the air,