I02 



STUDIES IN SEEDS AND FRUITS 



probably only one. Those of the closed pod on the tree are 

 characterised by permeability, by a large amount of water, and 

 by their inability to increase their weight when exposed in a 

 broken condition to the air. Those picked up from the 

 ground are mostly impermeable, and have a low percentage 

 of water, a deficiency associated with the capacity of consider- 

 ably adding to their weight by absorbing moisture when ex- 

 posed as broken seeds to the air. The behaviour of the seeds 

 of C^salpinia Sappan is probably typical of many leguminous 

 seeds with impermeable coats, especially in those cases where 

 the difference between the seeds would not be readily detected 

 by the eye. Strong winds and torrential rains would not 

 infrequently affect the somewhat premature detachment of 

 the seed from the parent. 



The seeds of Ipomcsa tuberosa, a convolvulaceous plant, offer 

 another good instance where divergent behaviour as regards 

 impermeability is not always associated with conspicuous differ- 

 ences in the aspect of the seeds. Whilst some of the seeds 

 swell in water, others have to be filed to induce absorption. 

 As shown in the results given below for the kernels, imperme- 

 ability is associated with a relatively small water-percentage and 

 a considerable absorptive capacity in air after being heated in 

 the oven. The permeable seeds, on the contrary, contain a large 

 amount of water and fall far short of their original weight when 

 absorbing moisture from the air after the heating process. 



Comparison of the Behaviour of Kernels of Ipomcea tuberosa 

 AFTER Exposure for two Hours to a Temperature of ioo° 

 TO 105° C. (The materials in each case were rather over 100 grains ; 

 the results are given in percentages.) 



