467 



of the special organ.s of the plant (as ears and tassel), nor to the less noticeable 

 but no less certain difference in the rate of srowth caused by a difference in the 

 stage of maturity; it assumes also that increase in the material in the plant, which 

 is doubtless the best measure of its growth, is accompanied by a proportional 

 development of plant organs. All that is claimed for it is tliat it serves quite well 

 for comparative purposes, even though it does not give results that are absolutely 

 correct. * * * Thecold,rainy spring very much retarded growth, so that measure- 

 ments were not begun till July 5, when the plants of both varieties were about 22 

 inches high. From August 5 to 9 all the plants tasseled out, after which, in 50 per 

 cent of the cases, little vertical growth occurred, though measurements were con- 

 tinued till the 17th, because of the slight increase in the remaining stalks. 



In the foUoAving table are shown the mean daily intervals of growth of the six 

 stalks : 



Comparison of toeather for 1SS7-89 during growth of corn. 



1887. 



Date of planting 



Date of first measurement 



Days of interval from planting 



Height attained inches . . 



Dat« at which greatest height was reached 



Days of interval from planting , 



Height attained inches.. 



Mean daily atmospheric temperature degrees . . 



Total rainfall inches . . 



Days on which more than 0.01 inch of rain fell 



Mean daily cloudiness 



May 12 



May 23 



11 



3.5 



July 23 



72 



80 



70 



8.3 



31 



4.2 



May 8 



June 18 



41 



10 



Aug. 8 



92 



81 



67 



11.5 



28 



4.9 



May 

 July 



Aug 



9 

 5 

 57 

 22 

 17 

 100 

 111 

 66 

 15.91 

 44 

 5.4 



The difference in temperature between these two seasons [1887 and 1889] is almost 

 equal to the ditference in the mean July temperatures of Quebec and Boston ; of Bur- 

 lington, Vermont, and Philadelphia; and of Fort Assiniboin, on the northern 

 boundary of the United States, and Santa F^, New- Mexico. Then, too, in 1889 the 

 rainfall was ahnost twice as great as in 1887, and the cloudiness at least 25 per cent 

 greater. 



The differences in the total vertical development attained are due to differences in 

 variety more than to differences in season, although undoubtedly, with a sufficient 

 temperature, ranker growth is to be expected with greater moisture. It may there- 

 fore be concluded that in our climate at least, when there is a rainfall of not less 

 than 8 inches during the period of growth up to the time when final vertical devel- 

 opment is attained, the temperature is the controlling element in effecting that 

 development. 



[Observations of the relative growth of the corn plant during day and night are 

 recorded in the following table:] 



