1 82 STUDIES TN SEEDS AND FRUITS 



there is no use for any free water in the economy of a seed 

 that has gone through the normal shrinking and drying 

 process. With these remarks I would now draw attention 

 to the contents of the following table, which is intended to 

 illustrate the hydratation of vegetable substances from this 

 standpoint. 

 Comparison One notices at once in the columns on the right side of 



?ontenS^or" the next table how constant in amount is the water of 

 leaves, fruits, hygroscopicity (the water of the air-dried tissue) in the living 

 leaf, fruit, and seed. Stated as a proportion of the living 

 substance, its amount varies usually between 3 and 6 per cent, 

 in different cases ; but since its quantity is regulated by 

 the degree of atmospheric humidity, it is evident that if 

 all experiments were conducted under precisely the same 

 conditions, the range of the variation would be much less, 

 probably only 4 to 5 per cent, for these different parts of 

 a plant. 



It is, therefore, not in the water of the air-dried tissue 

 (the water of hygroscopicity), but in the water lost by the 

 living tissue when drying under ordinary air-conditions (the 

 water of vitality) that the several parts of the living plant 

 differ from each other. This varies considerably, the range 

 of the results given in the table being 23 to 80 per cent. 

 But notwithstanding this variation, the most important sugges- 

 tion that this table offers to us is that the leaf, the fruit, and 

 the seed are, as respecting their water-contents, all comparable 

 in the living condition, the living seed being the soft uncon- 

 tracted seed, such as we see in the ripe capsule and legume 

 before drying begins. So, again, these parts of a plant are 

 all comparable in the air-dried state, the air-dried seed being 

 the typical resting seed. We cannot consider the seed as a 

 thing apart and place it in a category by itself. The resting 

 seed from this point of view is just as dead as the dried leaf. 

 Both are equally inert vegetable substances, and the only free 

 water that they both contain is what they yield up in the oven 

 and gain back from the air. Occasionally in the leaf, and 



