July 2, 1917 Variation of Water in Leaves of Corn and Sorghums 13 



Table II. — Evaporation (in cubic centimeters) for the different periods of leaf sampling 

 in 1 91 4, 191 5, and 1916, at Garden City, Kans. 



I.EAF SAMPLING 



The amount of water and dry matter in the leaves of a given variety 

 of plant was determined every two hours from 30 leaf samples, each with 

 an area of i square centimeter. Thirty representative plants of each 

 variety were selected and a leaf chosen on each plant for furnishing all 

 the samples for an experiment extending over the desired length of time. 

 Plate 3 shows the manner in which the leaf samples were obtained. 

 This figure shows the appearance of milo, corn, and kafir leaves at the 

 end of a 40-hour experiment. At 7 a. m. a single sample was taken 

 from each of the 30 selected leaves at a and toward the tip of the leaf. 

 This was done by means of a Ganong leaf punch taking an area of i square 

 centimeter. At 9 a. m. a sample was taken from each of the 30 leaves 

 at 6, directly opposite a. At 11 a. m. the samples were collected from 

 the leaves at c, directly below a, then at the next 2-hour period at d, 

 and so on. The samples for a 40-hour experiment were thus obtained 

 from a portion of the leaves representing less than 6 inches of their 

 respective lengths. The leaf samples from corn, kafir, and milo at any 

 period could be collected in the manner described in from five to eight 

 minutes. Care was taken in the selection of the leaves, so that they 

 would be as nearly the same age as possible for the three plants. The 

 uppermost fully developed leaf of each plant was the one from which the 

 leaf samples were obtained. 



The samples were collected in weighed vials which were then quickly 

 stoppered. The vials containing the moist material were weighed at 

 once on balances sensitive to o.i mgm. They were then placed in a 

 98972°— 17 2 



