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raise plants peculiarly fitted for wet climates or for cold climates, 
we begin with the seed that was ripened in wet or cold seasons. 
I think that probably a further prosecution of Linsser’s studies 
would have led to the conclusion that the influence of sunlight and dif- 
fuse sky light is the next important factor in vegetation, and that the 
quantity and quality of the seeds produced—that is to say, of the crop 
as distinguished from the mere epoch of ripening—depends upon the 
ratio of the nutrition carried up in the sap to the total intensity of 
sunshine. The grain harvests of the world may be divided into 
zones a, b, c, analogous to the phenological zones*that Linsser has 
given, and in which the quantity of the harvests is large when the 
nutrition is sufficient to use up all the sunshine, but is small when 
either nutrition or sunshine is deficient. As the plant begins a new 
cycle so soon as the last is finished and usually is delayed by the 
speedy approach of winter cold or autumnal drought, therefore 
Linsser’s laws would lead us to the conviction that by artificially 
regulating the temperature, moisture, sunshine, or artificial light, and 
the nutrition in the soil, we ought to be able to develop an ideal 
method of cultivation that should greatly increase the number of 
crops per year and the yield per acre, and especially so within small, 
limited areas that are protected by cover from injurious frosts. 
The need of water for the varieties of plants and seeds usually cul- 
tivated has led to great engineering projects for irrigation, and the 
scarcity of natural rainfall has led to wholesale condemnation of 
many arid regions as being unfit for profitable agriculture, but the 
progress of knowledge now shows us that nature has a power at work 
eradually overcoming these disadvantages, and that man by taking 
advantage of her ways may profitably cultivate crops in extreme cli- 
mates and soils, not so much by irrigation as by developing seeds and 
plants that suit the natural circumstances, just as our own ancestors 
developed our European grains from the grasses of Asia or our wide- 
spread maize from the weeds of Mexico. It is the duty of our agri- 
cultural experiment stations to lead the way in this evolution of new 
varieties quite as much as in the mere introduction or acclimatization 
and study of old varieties. Now that we have learned the secrets of 
Nature’s method of evolution we must hasten to apply it to the needs 
of mankind. 
DOVE. 
In 1846 H. W. Dove wrote as follows: 
In the tropical regions the mean temperature of any year differs 
but little from that of any other, but the quantity of rainfall differs 
largely. The result is that the yield of crops varies exceedingly, not 
only on lowlands that. depend upon the periodical floods of the rivers, 
but also on the islands, where there are no large rivers. Therefore 
in these climates the agriculturist cares less about the temperature 
than about the rainfall. 
