July 2,1917 Variation of Water in Leaves of Corn and Sorghums 37 



and 35.9 for milo. The minimum percentage of water on this basis 

 occurred for the three plants for the most part from i to 5 p. m. The 

 maximum percentage of water in the leaves of com occurred, during 1 1 

 nights, 7 times at 5 a. m., twice at 3 a. m., and twice at i a. m. The maxi- 

 mum percentage of water in the leaves of milo with but one exception was 

 found to be at 5 a. m. In 9 nightly observations of kafir leaves the 

 maximum percentage of water occurred 6 times at 5 a. m., once at 3 

 a. m., and twice at i a. m. The average difference between the mini- 

 mum and maximum percentage of leaf water during the night was 37.5 

 for com, 47.5 for kafir, and 40.0 for milo. The average range between 

 the maximum' percentage of water in the leaves during the night and 

 the minimum percentage during the day was 67.8, 67.2, and 51.2 for 

 com, kafir, and milo, respectively. 



VARIATION OF THE DRY MATTER 

 I. DRY MATTER PER SQUARE METER OF LEAF 



The dry weight of a given area of milo leaf was always found to be 

 greater than an equal area of either com or kafir leaves of the same age. 

 The average dry weight of a square meter of leaf for all the observations 

 made during these experiments was found to be 48.2 gm. for com, 52.5 

 gm. for kafir, and 56.2 gm. for milo. The average amounts of dry 

 matter per square meter of leaf during 17 days was 49.1, 54.1, and 

 57.4 gm., respectively, for corn, kafir, and milo, while, taken in the same 

 order, the average dry weight of the same area of leaves was 48.4, 

 53.4, and 56.9 gm. This makes an average difference in dry weight of 

 a square meter of leaf between the day and night of 0.7 gm. for corn 

 and kafir and 0.5 gm. for milo. These differences are much less than 

 one would expect; but a glance at the dry-matter curves shows that in 

 most cases there was a gradual increase in dry matter from 5 a. m. till 

 3 to 5 p. m., and that there was little depletion of dry matter before 7 

 p. m. After that there vv'as in most cases a gradual depletion of dry 

 matter in the leaves until 5 a. m. Since there was a gradual increase 

 of dry matter during the day and a corresponding decrease during the 

 night, the average leaf weight for the day and the night was practically 

 the same. 



The maximum amount of dry matter in the leaves of corn for 2 1 days 

 occurred 4 times at i p. m., 5 times at 3 p. m., 11 times at 5 p. m., and 

 once at 7 p. m. The dry matter of the leaves of milo for the same num- 

 ber of periods reached a maximum 6 times at 3 p. m., 14 times at 5 p. m., 

 and once at 7 p. m. In 17 day periods the leaves of kafir reached their 

 maximum amount of dry matter 7 times at 3 p. m., 9 times at 5 p. m., 

 and once at 7 p. m. On August 16, 191 6, the dry matter in the leaves 

 of all three plants never increased over what it was at 7 a. m. It is seen 

 from the figures quoted above that the maximum amount of dry matter 



