COMMODITIES 
I. COMMODITIES DEPENDENT DirecTLY OR INDIRECTLY ON CLIMATE 
A. Products of the Temperate Zone 
233. WHEAT. This, the most valuable of all the grains of tem- 
perate climates, has been cultivated from the remotest antiquity. 
The remains discovered at the lake-dwellings of Switzerland belong- 
ing to the Neolithic period, or New Stone Age, show that at that time, 
long before the beginning of written history, as many as five different 
varieties of wheat were already in cultivation. The crop early acquired 
an important place as an object of agriculture in all parts of the tem- 
perate zone in the Old World where the climate was favourable to it, 
and gradually extended its domain at the expense of other crops which 
In certain regions were more easily grown, but which yielded a less 
valuable grain. Though in the New World wheat, like most other 
grain crops, was unknown in the time of Columbus, its cultivation has 
since spread there to such an extent that Europe now makes up by 
supplies obtained thence the greater part of her own deficiency in this 
cereal. In Australasia also this grain is now in general cultivation, 
and in fact there is no part of the world with a suitable climate and a 
sufficient population where wheat is still unknown. 
234. A crop so valuable, so widespread, and so long in cultivation 
could not fail to exhibit a great number of varieties and to show 
the result of past care in improved quality. The varieties of wheat 
cultivated at the present day yield larger grains than those of the 
ancient lake-dwellings. The number of the varieties now grown is 
probably in a literal sense countless, new varieties constantly being 
produced. Very often these varieties, as in the case of other cultivated 
plants, manifest strong local preferences, and do not flourish except 
in particular regions. The seeds of English wheat fail in India ; and, 
on the other hand, the wheat-growing region of northern India, in 
which the crop has to ripen during the cool season (1047, 1053) before 
the advent of the scorching heats of summer, has developed varieties of 
wheat which ripen in a shorter period than those of colder climates, 
but which pine and dwindle when an attempt is made to grow them 
n England. It is still more important that varieties have been de- 
veloped which ripen in the short summers of the Canadian north-west