230 



STUDIES IN SEEDS AND FRUITS 



The Acacia 

 seed. 



Old seeds 

 and in- 

 organic sub- 

 stances. 



Professor Ewart respecting the matter are opposed to the 

 position adopted in this work. It has been established by my 

 observations that the impermeable seed, more especially the 

 leguminous seed, holds much less water in the entire state than 

 when broken up and exposed to the air. The process of the 

 change is exhibited when the seed develops some defect in its 

 coverings or when we imitate such a defect by puncturing 

 the coats. The seed then slowly gains in weight by abstracting 

 moisture from the air, until in time it assumes the stable 

 hygrometric condition of an ordinary permeable seed. 



Now, Professor Ewart takes a very different position. In 

 the case of Acacia seeds, which are notable for their imperme- 

 ability, and often contain less than 5 to 8 per cent, of water, he 

 writes that " such seeds when preserved in a dry atmosphere 

 seem to steadily lose water, until ultimately as dry as if kept in 

 a desiccator " (Proceedings of the Royal Society of Victoria^ vol. 

 xxi. p. 199, 1908). This is based on the fact that old seeds 

 lost less weight in the oven than fresh seeds. Fresh air-dried 

 Acacia seeds, he says, contain 5 to 14 per cent, of moisture ; 

 seeds ten to twenty years old contain from i to 3 per cent. ; 

 whilst fifty-year-old seeds hold less than i per cent., losing 

 only O'7 per cent, of their weight after the prolonged exposure 

 of a day to a temperature of 1 10 C. Fine capillary glass tubes, 

 he writes, show a greater loss of weight than this, and hence 

 he infers that " old, dry, cuticularised macrobiotic seeds become 

 drier than corresponding inorganic material." 



Professor Ewart thus observes that in course of time Acacia 

 seeds become as dry as if kept in a desiccator, and implies that 

 they behave like inorganic material. This raises the question 

 as to the behaviour of these two types of substances after 

 desiccation. Seeds that have been exposed to such a low 

 temperature that the free water has been completely expelled 

 fall to powder when struck with a hammer and quickly absorb 

 the hygrometric water from the air (P. Becquerel, in Annales 

 des Sciences Naturelles^ Botanique, tome v., 1907). This is 

 but an extreme form of what occurs in the kernel of an 



