142 



STUDIES IN SEEDS AND FRUITS 



much on the imperfection of the method as on the failure of 

 the seeds, since, as above remarked, experiment has established 

 the ability of certain seeds to withstand for some hours a 

 temperature of 100 to 120 C. However, the original 

 purpose of this experiment has been served in demonstrating 

 the protection an impervious covering affords against extreme 

 thermal and hygrometric conditions. 



Very different is the behaviour of the permeable seed 



under the strain of a high temperature, a difference which its 



The be- hygroscopicity would lead one to expect. Permeable seeds 



permeable give up their moisture in the oven almost as readily when 



seeds under^ protected by their coverings as in the exposed condition. 



ature. Since we have already seen in the chapter on type seeds that 



with such seeds the coats merely restrain but do not prevent 



the hygroscopic reaction of the kernel, the results given below 



are such as we should have looked for. 



TABLE SHOWING THE INFLUENCE OF THEIR COVERINGS ON THE BEHAVIOUR 

 OF PERMEABLE SEEDS WHEN EXPOSED FOR TWO HOURS TO A TEMPER- 

 ATURE OF 100 TO no" C. 



(Two samples of each kind of seed were employed, one with the seeds entire, the 

 other with the seeds cut across so as to be deprived of the protection of their coverings. 

 The seeds were eight or nine months old, the samples of the peas weighing 100 grains 

 and of the others 200 grains. The results are given in percentages. ) 



By contrasting the results above tabulated with those given 

 a few pages back for Entada scandens and Guilandina bonducella^ 

 where the seeds were exposed to the same test, we can frame 

 a numerical estimate of the difference in the degree of protec- 

 tion against high temperatures which the coverings offer in the 



