FATE OF SEEDS INDICATED BY BALANCE 237 



extending over three years and nearly two years, the amount 

 of the change being i-i to i-6 per cent, of the total weight. 

 In all cases the seeds were heavier at the beginning than at 

 the end, a result due to their being kept at first in a damp 

 room. The variation is the normal hygroscopic reaction. 

 There is no sign of any permanent increase in weight. If 

 one was guided only by the run of the figures and disregarded 

 the conditions of the experiment, one might infer that these 

 seeds lose weight as they get older. 



The permeable and variable seeds now under observation The author's 

 with the object of testing the influence of time on their i^g^expefi-" 

 weight belong to nearly thirty genera, of which one-third '"^"'^• 

 are leguminous, and include Abrus, Achras, Anona, Casalpinia, 

 Canavalia, Citrus, Datura, Erythrina, Faba, Hura, Iris, Luffa, 

 Morinda, Phaseolus, Pisum, Ricinus, Thespesia, etc. 



In conducting all experiments of this kind it is, as already whilst with 

 remarked, a matter of necessity that the seed should have slmUarfruTts 

 acquired a stable weight, either as an impermeable seed when, ^^^ ^^% 

 with regard to the hygroscopic reaction, it is absolutely inert, complete the 

 or as a permeable seed when it displays a small variation on cess°^fore' 

 either side of a mean. It is not merely requisite to employ n^^f^n jg_ 

 resting seeds for the purpose, but they must be resting seeds tached, the 

 with a stable weight. The seeds of the berry and of the legume moist, fleshy 

 when first liberated by the opening or by the decay of the half of "their 

 fruit are, as described in subsequent chapters, in very different weight after 

 stages of drying. In both cases the seed may in colour, liberated, 

 hardness, and other features have the appearance of a normal 

 resting seed. Yet if it belongs to a berry it has still to lose 

 40 or 50 per cent, of its weight by drying in air ; whilst if 

 it belongs to a legume it will have already practically completed 

 the drying process. It is true, as shown below, that legumin- 

 ous seeds usually lose slightly in weight after being gathered 

 from the dehiscing pod ; but here we must often be anticipating 

 nature a little. I have not many observations bearing on this 

 point, but they are sufficient for the purpose of illustration. 



With regard first to the impermeable seeds of legumes, my 



