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this season of its growth the plant really needs less water than before, 
but still its roots have the same power of absorbing water, and if the 
sap is thus diluted there results a seed or fruit that is heavy with an 
excess of water. Of course this water will dry out, if it has an 
opportunity, after the harvest, but if it has no opportunity, on account 
of damp weather, it will remain in the seed and render the latter more 
subject to injury from fungi, whose spores are always floating in the 
air seeking a moist nidus or resting place favorable to their growth. 
Such moist seeds give a heavy, green harvest, but a light dried crop. 
Thus it happens that the distribution of atmospheric heat, and 
moisture, as to time, is quite important in its effect on the local harvest. 
Apparently the time of ripening of the harvest depends wholly 
upon the chronological distribution of water and sunshine, but the 
quantity and quality of the harvest, which are the important practi- 
eal results to the farmer, depend upon the nutrition carried into the 
plant by the water that is absorbed by the roots. 
IRRIGATION. 
The determination of the right time for irrigation and of the 
proper quantity of water, in order to produce the best crop in soil 
of a given richness is the special problem of those planters who 
depend mostly upon irrigation for successful agriculture. In general 
it may be said that our ordinary seeds have long since been selected 
and acclimatized with a view to success in a climate where abundance 
of moisture is available at the proper season. Hence our crops are 
not so likely to be injured by excess of rain as by deficiency or 
drought. Therefore in almost every section, from the Rocky Moun- 
tains to the Atlantic, the highest success can only be attained by mak- 
ing provision for artificial irrigation in times of drought. The exact 
times and quantities of irrigating water depend upon the seed, the 
soil, and the evaporation, which latter is due to dryness of the air, the 
velocity of the wind, and the character of the soil; but when artificial 
watering or irrigation is needed to supplement natural rain one must 
seek to approximate as closely as practicable to the conditions 
presented in the countries where the seed originated, and especially 
the conditions presented during the seasons in which the given seed 
produced the best crops. 
IMPORTANCE OF CLIMATIC LABORATORIES. 
The studies that we are entering upon are greatly facilitated by 
experiments on a moderate scale under conditions that are under the 
control of the investigator, and free from the irregularities of open- 
air agriculture. The laws of nature can only be found out by ques- 
tioning nature, as it were, by means of test experiments. Our present 
