The hygro- 

 scopic be- 

 haviour of 

 pods. 



174 



STUDIES IN SEEDS AND FRUITS 



to the eye there was a marked increase of weight and a slight 

 softening of the aiFected materials. 



But I may remark that the more moderate view of the 

 range of hygroscopic variation for seeds is supported by the 

 results of my observations on air-dried fruits. Some of them 

 relating to pods or legumes are tabulated below. 



A. — Results of Experiments on the Hygroscopic Range of entire 

 Air-dried Legumes or Pods, indehiscent and containing their 

 Seeds. (The hygroscopic range is the variation in weight stated as a 

 percentage of the total weight.) 



^oie. — In all the experiments except that on Pea-pods, the pods were kept in one 

 room. The experiments, occupying two months, lasted from June to August, The data 

 for the Pea-pods were obtained by transferring them from a cool and moist room 

 (temperature 50° to 55° F.) to a warm and dry cupboard (temperature 65° to 70° F.) and 

 weighing them after four days. 



B. — Comparison of the Hygroscopic Ranges of the Air-dried Seeds 

 and Fruit-case of Pisum sativum (Pod) and of Iris fcetidissima 

 (Capsule) under the same Conditions. 



Iris fcetidissima 

 Fisum sativum . 



H. R. of seeds 4*0 per cent, 



4'S 



H. R. of fruit-case 3 '6 per cent, 

 II II 47 11 



It will be seen from these tables that the variation in weight 

 in response to the changes in atmospheric humidity was usually 



