89 



of carbohydrate molecules in the chlorophyll celU, are not notahlv 

 diminished by filtration through aqueous vapor. 



The distribution of the sunshine as indicated by the numl.er of dear 

 days in each month is also an interest ing part of the problem. Kn>in 

 the chart. Washington and AIIH-S appear to have had the nio^t unifonu 

 distribution of dear days that is. the number was <|uite uniform for 

 each month. The smallest number of clear da\> \\a^ experienced at 

 Madison; especially is this true of May, June, and September. The 

 largest numl>er of clear day- \\a- experienced at Ames. ,!ulv and 

 August being conspicuous in this particular. Ithaca stand- next to 

 Madison in regard to the small number of clear days, having alnnt 

 the same record. As in the case of sunshine, it mii-t be >;iid that the 

 actual ])redominance of clear days is not to be reckoned a> an important 

 factor, except in so far as it may indicate drought, and thus interfere 

 with the magnitude of the crop. Thus the large number of clear davs 

 at Ames was accomplished by excessively dry weather in 11M.H. 



Chart No. '2 shows the percentage of sugar in the beet, the purity of 

 the juice, the temperature, and the average length of day at the Nation. 

 The most interesting feature of this chart is the relation between the 

 average length of day and the sugar in the beet. Eliminating, as in 

 the case of latitude, the Blacksburg station, where the days, on account 

 of the southern latitude, were short, and ignoring the slight variation 

 at Lafayette, we rind that there is a general agreement in the direction 

 of the two curves, representing the percentage of sugar in the beet 

 and the length of the day. In other words, it may be generally stated, 

 as the result of an inspection of this chart, that the percentage of sugar 

 in the beet increases with the length of the da\ T . This is in harnionv 

 with the commonly accepted theory of the correlation of the functional 

 activity of the chlorophyll cells and the light of the sun. Tinier the 

 same general conditions it is evident that the longer the hours of 

 activity the greater the amount of work accomplished: hence, with 

 longer hours of sunlight the quantity of carbohydrates formed will be 

 greater. 



The temperature curve, as in chart '2 of Bulletin I4. crosses the 

 curve of sugar content, but not symmetrically, as in the chart just men- 

 tioned. One reason of this hick of symmetry i> the low temperature 

 of the Blacksburg station. On the other hand, a phenomenally high 

 temperature is recorded for the Lafayette station. While showing 

 more irregularities than the curves representing latitude and length 

 of day, it is yet evident that the tendency of the Migar i- to dimini>h 

 as the temperature increase's. The purity curve. a> wa> to be expected. 

 follows in general the percentage of sugar in the beet. 



Chart No. 3 shows the percentage of sugar in the beet, the altitude 

 of the station, and the rainfall record, both the totals and the distri- 

 bution bv months. 



