CHAPTER IV 



PERMEABLE AND IMPERMEABLE SEEDS 



THE observations and experiments on the results of which 

 the four following chapters are based cover the period of 

 1 906 to 1911. They were practically completed, and the 

 greater part of the results elaborated and written out, before 

 the works of other investigators had been consulted. In this 

 condition they have been in the main reproduced in these 

 pages, as I thought it best that they should tell their own 

 story, my original purpose having been to make an in- 

 dependent study of the impermeability of seeds without 

 being influenced by the ideas of others. That has been 

 done ; but in the final summing up of my own results 1 

 have been guided in the estimate of their value and in the 

 drawing of my conclusions by the results obtained and the 

 opinions formed by other inquirers. 



In order to introduce the subject and to give method to Comparison 

 the arrangement of the results of a large number of observa- fGuilandina 

 tions and experiments, I will take the very divergent behaviour, and d Cana* 

 as revealed by the balance, of the seeds of two leguminous vaiiaensi- 

 plants, Guilandina bonducella and Canavalia ensiformis. The 

 first named has a very hard grey seed of the size and form 

 of a marble, weighing usually about 40 grains, and possessing 

 very thick coats. The second has a thin-skinned white seed, 

 about 20 millimetres long, weighing 20 to 25 grains, and 

 typical of a large number of leguminous plants. (See Note 

 5 of the Appendix.) 



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