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FIG. 7.-Comparison of sugar content and latitude for the five stations completing the entire five

years of the experiment.

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FIG. 8.-Comparison of sugar content and length of day for the five stations completing the entire five

years of the experiment.

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FIG. 9.-Comparison of sugar content and temperature for the five stations completing the entire five

years of the experiment.

The basic curve in each of the four charts is the content of sugar at the different stations, which are arranged in order of sugar content. For the purpose of securing a better comparison this curve is reduced to a straight line. The straight line is so placed as to represent as nearly as possible the mean variations of the curve. In other words, an attempt is made to represent in a straight line the total change in the sugar content at the five stations on the supposition that the magnitude of the change was the same for each successive station. On each of the charts there is platted in order one of the four other factors already alluded to, viz, latitude, length of day, temperature, and purity. In each case, however, the curve is platted according to the data collected and the straight line is drawn representing the mean value of the curve. While, of course, it is almost impossible, without the use of elaborate calculations, to exactly place a line of this character, the straight lines on the charts represent approximately the mean values of the curves.

It becomes easy to distinguish at once the general relation which exists between the sugar content and the factor of the environment represented in each case by the straight line drawn as above described. Any detailed description of these final graphic charts is unnecessary, as a glance at the st aight lines of each chart shows the intimate relations existing between the sugar content and the other factors. mentioned. In the case of latitude and length of day, the two straight lines having the same origin diverge only slightly from that representing sugar content, and the straight lines for purity and sugar content run still more closely together. The platted and the computed lines for sugar content coincide on Charts 9 and 10 between the points representing Ithaca and Geneva. In the chart representing the relation of the temperature to sugar content it is seen that the straight lines make almost a perfect X. These final graphic charts. represent, therefore, in the simplest form of expression, the rations which have been established by the studies conducted throughout a period of five years.

We have now reached the end of this long and laborious research, and while there are many points in connection with the influence of environment which are not clearly brought out, it is believed that the major factors have been determined with considerable accuracy in regard to their influence on the composition of the beet.

The great extent of our country affords exceptional facilities for studying the effect of environment in widely separated localities. In former studies by this Bureau the chemical composition of cereals a

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@U. S. Dept. Agr., Division of Chemistry, Richardson, Bul. No. 1, An investigation of the composition of American wheat and corn, 1873; Bul. No. 4, ibid., 1884; Bul. No. 9, Third report on the chemical composition and physical properties of American cereals, wheat, oats barley, and rye, 1886.

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FIG. 10.-Comparison of sugar content and purity at the five stations completing the entire five years

of the experiment.

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