126 



STUDIES IN SEEDS AND FRUITS 



The neces- 

 sity of con- 

 fining the 

 inquiry to 

 seeds of the 

 same order. 



Leguminous 

 impermeable 

 and perme- 

 able seeds 

 contrasted. 



of other orders, we should find that there is often no sort of 

 relation between them as regards the capacity of absorbing 

 water from the air in the broken condition and the actual 

 water-contents as indicated by the loss of weight in the oven. 

 For example, an average impermeable seed which contained 

 9 per cent, of water would be able to increase its weight by 

 about 7 per cent, when broken up and exposed to the air. 

 It would be ultra-dry in the entire condition to that extent. 

 On the other hand, this percentage of water in oily seeds like 

 those of Ricinus or Hum or El<eis would be no indication of 

 dryness in the seed, since except for the hygroscopic variation 

 they would remain unchanged in weight on exposure to the 

 air in the broken condition. Here matters are on quite 

 another plane, and for a valid comparison of seeds of different 

 orders we must not look in this direction. It is therefore 

 requisite, if we wish to connect the seed's capacity of in- 

 creasing its weight by abstracting water from the air with its 

 deficient water-contents, that we should restrict the comparison 

 to seeds of the same order. In this case we take leguminous 

 seeds ; but even here disturbing influences may come into 

 play, though they are more easily avoided. 



So, confining ourselves at present to the Leguminosae, we 

 will at first refer to the indications afforded by impermeable 

 seeds in the table that a seed's capacity of increasing its weight 

 when bared of its coats or in the broken condition is determined 

 by a low water-percentage. 



We can see at once in the results for impermeable 

 leguminous seeds that the seeds which lose least weight when 

 submitted to a temperature of 100 C. are those which add 

 most to their weight when exposed unprotected to the air. 

 Thus, we see that the three kinds of seeds with the lowest 

 water-percentage, Dioclea reflexa, Guilandina bonducella^ and G. 

 bonduc^ are those which add most to their weight when exposed 

 to the air. On the average these seeds with a water-percentage 

 of 7*5 per cent, add 9-2 per cent, to their weight when exposed 

 in the broken condition to the air. The other impermeable 



