1 32 STUDIES IN SEEDS AND FRUITS 



From these similar samples we learn that as a rule exposure 

 to a temperature of 100 C. for from i^ to 2 hours but little 

 affected the capacities of either the seed-coverings or the 

 kernel for increasing their weight by absorbing moisture 

 from the air in the broken condition. It is scarcely worth 

 while to labour this point. The same indications are supplied 

 in the case of other impermeable seeds mentioned in the table, 

 such as those of Dioclea reflexa, Guilandlna bonduc^ Mucuna 

 urens, etc., and by the samples of variable seeds where im- 

 permeable seeds predominated, such as those of Ctesalpinia 

 Sappan, Erythrina corallodendron, etc. 



The be- Coming to permeable seeds of the leguminous type, we 



permeable notice in the table that during the period of five days 

 seeds. following the exposure to a temperature of 100 C., they 



all regained from the air most of the water lost in the oven. 

 That they failed to return to the original weight is doubtless 

 to be attributed to the limited duration of their exposure 

 to the air, since it is clearly shown in the instances of Faba 

 vulgaris, Phaseolus multiflorus, and Pisum sativum on p. 142 that 

 if the test had covered a period of a week or two instead of 

 only five days, the seeds would have regained their original 

 weight. But they would not have displayed any excess, 

 except such as is included in the ordinary hygroscopic varia- 

 tion of about 3 per cent., and this is the great point of 

 contrast between permeable and impermeable seeds. 



As respecting permeable seeds other than those of the 

 Leguminosae, the data for several kinds given in the table tell 

 much the same story. After exposure to the same tempera- 

 ture of 1 00 C., they in most cases regained much of their 

 lost weight by taking up water from the air, and, no doubt, if 

 the test had been prolonged, they would have regained all. 

 The behaviour of the seed-coverings of the Shaddock (Citrus 

 decumana] is abnormal, but I can throw no light on it here. 

 However, taking all the data for permeable seeds given in 

 the table, it is evident that whether leguminous or otherwise, 

 they as a general rule behave in the same way after being 



