2.34 STUDIES IN SEEDS AND FRUITS 



during the next twelve months, when the experiment ended. 

 I did not finally test the water-contents, but the fact that in 

 the last year the seeds exhibited a hygroscopic variation of 1-4 

 per cent, indicates that they must still have held a fair amount 

 of water. But against this indication of Professor Ewart's 

 view must be placed the indications of another experiment 

 on the same seeds, the results of which are also tabulated in 

 Chapter IV. Here I merely filed through the impervious 

 shell, and thus enabled the air to have access to its ultra-dry 

 kernel within. During four months the seed slowly added to 

 its weight as much as 1 1 per cent. ; but at the end of the 

 experiment, which covered two years, the seed was still about 

 8 per cent, heavier than before its shell was filed through. 

 Possible However, a solution of the difficulty seems to be offered 



the difficulty, by Professor Ewart's remark, when discussing the drying in 

 time of Acacia seeds, that " it is as though the cuticle allowed 

 traces of water to escape externally, but none to enter " (ibid. t 

 p. 199). From this I am inclined to think that his oven- 

 experiments for testing the water-contents were carried out on 

 the seeds whilst protected by their hard, impervious coats. If 

 so, this explains the whole matter. In my experiments on the 

 impermeable seeds of Entada scandens and Guilandina bonducella^ 

 which are described towards the close of Chapter VI., I show 

 that when exposed both in the entire condition and in the 

 broken condition to a temperature of 100 to 110 C. for two 

 hours, the seeds in their hard coverings lost only about a 

 fourth of the water lost by the seeds no longer protected by 

 their coats. It was also elicited that the seeds in their cover- 

 ings subsequently made little or no attempt to regain the 

 moisture from the air and doggedly maintained their imper- 

 meability. Thus Professor Ewart's surmise that the coats of 

 a seed allow the water to escape, but inhibit re-absorption, is 

 certainly applicable to the behaviour of an impermeable seed 

 during and after the oven test. But this does not reproduce 

 the conditions of drying at ordinary temperatures in the course 

 of years. 



