82 JOHN W. SHIVE AND WILLIAM H. MARTIN 



same day is 1.29. This indicates that the indices of transpiring 

 power for the sprayed leaves average 23% higher than for the un- 

 sprayed leaves of the same plant (series B), and 29% higher than 

 for the leaves of the unsprayed plant (series C). A comparison, 

 similar to the one made here, of the ratio values derived from 

 the data of August 18, considered in connection with table 1, 

 shows that the indices of transpiring power for the sprayed 

 leaves average 21% and 18% higher than the corresponding 

 indices for the unsprayed leaves of the same plant (series B) 

 and for the leaves of the unsprayed plant (series C), respectively. 



It is interesting to note in this connection the results obtained 

 by Duggar and Cooley'^ with potted tomato plants. In an 

 experiment extending over a time period of more than three 

 weeks, during which quantitative measurements of transpira- 

 tion were made, these authors found the water loss per gram 

 of green substance from ten plants sprayed with strong Bordeaux 

 mixture (4-6-50 formula of agricultural practice) and from ten 

 similar plants sprayed with weak Bordeaux mixture (2-3-50 

 formula) to be 25% and 13% higher, respectively, than the cor- 

 responding water loss from ten similar unsprayed plants. In 

 a similar experiment extending over a time period of sixteen 

 days, Martin'^ found the water loss per gram green substance 

 and per gram dry substance from six potted tomato plants 

 sprayed with Bordeaux mixture (4-4-50 formula) to be 7% and 

 9% higher, respectively, than the corresponding water loss from 

 six similar unsprayed plants. While the results noted are not 

 strictly comparable with those here obtained by means of the 

 method of standardized hygrometric paper, it appears that such 

 a method as the one here employed with plants under cultiva- 

 tion, may be expected to yield results which are in entire ac- 

 cord with those obtained by means of the quantitative methods 

 usually employed. 



The three separate series of hourly index values for entire foliar 

 surfaces, given in tables 1 and 2, are represented graphically in 

 figure 1. Here the abscissas indicate the hours (numbered 



i« Duggar, B. M. and Cooley, J. S., 1914, p. 19, /. c. 

 "Martin, W. H., 1916, p. 546, I. c. 



