312 STUDIES IN SEEDS AND FRUITS 



atmospheric humidity, the shell or pericarp loses 72*8 percent, 

 of its moist weight, the seed 59*2 per cent., and the fruit in its 

 entirety 64*4 per cent. Such are the indications given in the 

 columns of this table for the acorn gathered at this date. 

 When we compare them with those fruits collected earlier and 

 later, we find that during the acorn's growth the seed steadily 

 increases its weight and decreases its water-contents long after 

 the pericarp has ceased to grow and has begun to dry. 



This table will be noticed in different connections, but 

 especially in relation to vivipary or germination on the 

 plant in Chapter XIX. With these explanatory remarks 

 I will now proceed to refer more in detail to the particular 

 lesson which the data furnish us here respecting the develop- 

 ment of the acorn on the tree, namely, the continued growth 

 of the seed after the fruit-shell has begun to lose its vitality. 

 This is not only the tale of the balance ; but it is the story that 

 the acorn, as we handle it, conveys to us plainly enough in the 

 increase in size, weight, and solidity of the seed, whilst the 

 shell is becoming thinner and drier in the " browning " process. 



The tendency of a seed in some cases to continue its growth 

 after the fruit-case or pericarp has begun to lose weight and 

 dry, in other words, to die, finds its final expression in the 

 germination of the seed on the plant. To put it in another 

 way, it is a step towards vivipary. It is not by a mere coin- 

 cidence that I am enabled to bring into touch with the 

 viviparous habit all the three plants that have before been 

 mentioned as illustrating the normal growth of the seed after 

 the pericarp has begun to dry and to lose its vitality. In the 

 cases of the Oak and the Coco-nut Palm, the connection is 

 more or less direct, whilst with Barringtonia speciosa the implica- 

 tion is only indirect. 



Thus in Chapter XIX I have dwelt upon the tendency to 

 vivipary displayed by the nuts of the Oak {Quercus Robur), 

 as observed by me during successive years at Salcombe in 

 Devonshire. That the coco-nut does occasionally " sprout " 

 on the palm came under my notice in Fiji {Plant Dispersal^ by 



