ADDITIONAL EVIDENCE 119 



Speaking very generally, however, we may infer that legu- 

 minous impermeable seeds when bared commonly increase 

 their weight from 5 to 10 per cent, by abstracting moisture 

 from the air. 



A question of interest here presents itself as to the 

 duration of the ultra-dryness of the kernels of impermeable 

 seeds. My materials for furnishing an answer, though 

 insufficient, tend to show that this condition may be main- Duration of 

 tained for several years. A seed of Mucuna urens, gathered dryness^of 

 by me from the plant in Hawaii eleven years before, impermeable 

 increased its weight when bared of its coats in England 

 6*5 per cent, in ten days. In the same way, the bared 

 kernels of two seeds of Guilandina bonducella obtained by 

 me in Fiji ten years before added 7*2 per cent, to their 

 weight ; and a seed of Strongylodon lucidum, picked up amongst 

 the drift on a Fijian beach eleven years before, and perhaps 

 a year or two old then, increased its weight by 6 per cent, 

 when bared in England of its coats. In the case of the 

 two last-named species, seeds collected at the same time and 

 place and tested for germination at the time of the above 

 experiment germinated healthily and supplied plants for my 

 greenhouse. 



There is but slight indication here of any marked decrease 

 in the ultra-dryness of impermeable seeds during a period of 

 ten or eleven years. The increase in weight {6-^ per cent.) of 

 the seed of Mucuna urens is rather above the average (6-o per 

 cent.) for three seeds, six to eighteen months old, which were 

 also tested in England. On the other hand, the rate of increase 

 for the Fijian seeds of Guilandina bonducella ten years old 

 (7 "2 per cent.) is considerably under the average for the 

 tropics (15 per cent.). However, the contrast is not nearly so 

 great as it appears, as the Fijian seeds were experimented on 

 in England, and, as shown in the table below, the rate of 

 increase of the weight of the bared seeds of Guilandina 

 bonducella in a temperate climate would average only about 

 10 per cent. 



