Jan., 1920] Resistance of Leaves to Transpiration 69 



deficit. The variations in the transpiration rates are not 

 proportional to the wind velocity or to the evaporation although 

 there is some increase due to the wind-. The total daily ratio 

 for this experiment is 0.65. 



In order to bring the results of the first four experiments 

 together in a more compact form, a table of totals and ratios 

 was made. This table (Table III, page 84) gives total day, 

 night and daily rates of transpiration and evaporation for each 

 experiment, and in experiment 2 and 4 the total rate for the still 

 air and the wind intervals. The mean temperature and 

 saturation deficit for each corresponding period are also shown. 



Series II. There are twelve experiments in this series 

 which is divided into four sub-series of three experiments 

 each. The same plants were used throughout the entire series. 

 The transpiration rates of three mullein plants were obtained 

 by the same method as in series I. In series Il-a the normal 

 plants were used, but in the rest of the experiments the hairs 

 were removed from the upper leaf surfaces of one plant and from 

 the lower leaf surface of another, while the third plant was 

 left normal throughout the series. Each sub-series has some 

 condition changed or modified, as in the different experiments of 

 series I, which are given in the accompanying table. 



Series II. 



Series Il-a. Normal plants, greenhouse, still air. 



Series Il-b. Hairs removed, greenhouse, still air. 



Series II-c. Hairs removed, greenhouse, wind. 



Series Il-d. Hairs removed, darkroom, still air. 



Series Il-a. Experiments 5, 6 and 7, which are the 

 results of this sub-series are given on pages 78-79, in a 

 tabulated form, and on page 66 in the form of curves. 

 These results show the daily march of transpiration and give 

 a record of the common factors influencing water loss from 

 plants. These curves represent the ordinary rates of water 

 loss from plants of this type. Table IV, on page 84, which 

 gives totals and ratios for this series, shows that even from 

 plants of the same species under the same conditions, the rate 

 of water loss is not necessarily the same. This is shown by 

 i:he ratios given in this table as well as by the total rate of water 



