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as bushels or pounds, since the absolute crop depends so much upon 
the soil, the manuring, the cultivation, the thickness of seeding, and 
other details. On the other hand, the crop of one season must have 
some relation to the crop of the preceding season by reason of the 
inherited tendencies of the seed from which it was raised. The cli- 
rainfall or useful moisture rainfall or nutriment 
temperature or heat ith sunshine 
are, as shown by Linsser, the data that must be compared with the 
resulting harvests. 
(4) It is evident that the question of the effect of climate on a 
given crop in the past is not so important as the prediction of what 
crop will be harvested from a given field already planted. On this 
point I have given all the illustrations that I could find, especially 
in Chapter XII, showing how from an analysis of a sample at any 
given date one should be able to predict the resulting crop. The 
result can be made correct to within 10 per cent, if we allow for the 
ordinary average irregularities of the climate, a statement of whose 
extent can easily be made up from meteorological records. As to 
extraordinary irregularities of climate which can not be foreseen, I 
remark : 
(a) First of all the effects of excessive droughts at each stage of the 
plant can be estimated from the experimental data given in Part I, 
and will be found to harmonize as well as could be expected with the 
results of actual experience as given in Part II: 
(b) The effect of severe unusual droughts, or heat, or cold, or mois- 
ture are ordinarily felt over relatively small portions of the country, 
so that the average result is small in comparison with the whole 
crop available in the country; for instance, in 1890, in Kansas 
and Nebraska the corn harvest was one-half of its usual amount and 
almost the same in 1887, reckoning, of course, the yield per acre, 
but this and the corresponding small yields in a few other States 
represent only an inappreciable percentage of loss to the country at 
large. 
(5) The studies of the effect of climate on the daily development 
of sugar in beets, sugar cane, or sorghum, or on the nutritious harvest 
of grass and cereals has shown the approximate best dates for harvest- 
ing these crops. 
(6) The studies of the physiological importance of the leaves of 
beets will eventually show whether these should be trimmed or how 
they should be treated in order to stimulate the production of sugar. 
As the pruning of hop vines and grapevines stimulates the ripen- 
ing and increases the amount of the crops, and as the plucking of 
the tassels from the maize apparently increases that crop, and as the 
plucking of the flowers and balls from the potato vines increases the 
growth of the tubers, so doubtless in many other ways the methods of 
matie factors 
