5o6 STUDIES IN SEEDS AND FRUITS 



against the view that seeds must absorb a certain quantity of water in 

 order to germinate. But the minimum amount of water requisite, as 

 dealt with on p. 43, is the water needed to start the germinating 

 process in a resting seed after a period of complete repose. The seeds 

 of Cr'inum and the acorn never actually enter upon the rest-period. 

 Accordingly the quantity of water requisite to sustain the growing 

 process would, it is likely, be far less than the amount needed to re- 

 kindle the vital activity of a resting seed. This is consistent with the 

 familiar principle that it takes more energy to start a machine than to 

 keep it going. 



From the above table it is to be inferred that whilst the seed in its 

 entirety lost 57 per cent, of its weight during these four months, the 

 embryo increased its weight 8| times. We also perceive that this 

 change was accompanied by corresponding changes in the size of the 

 embryo, and that notwithstanding its growth it participated in the 

 drying of the seed. As the embryo grew in the drying seed the 

 proportion of its water-contents decreased. 



Correction. — For '' ten or fifteenfold " in the Crinum paragraph on 

 p. 436, read "nine or tenfold." 



NOTE 30 (p. 448). 



The conditions for Jiowering. 



There is much to support the view that the vegetative mode of 

 reproduction in plants is based on purely terrestrial necessities and that 

 the flowering and seeding stage represents the plant's effort to return 

 to its general cosmic habit. When Schimper remarked that the 

 correlation between the production of flowers and the seasons of the 

 year is an adaptation to external factors on the part of physiologically 

 necessary processes, and that this dependence in the reproductive 

 domain is a secondary feature [Plant Geography^ p. 252), he opened up 

 this question. When also he observed that the cardinal degrees for 

 the growth — and perhaps for the inception — of the primordia of 

 flowers are often much lower than for the growth of vegetative shoots, 

 so that the former are favoured by a relatively lower temperature, and 

 the latter by a higher temperature, during development (p. 48), he 

 showed clearly in which direction the inquiry lay. Warmth, shade, 

 moisture, and a rich soil favour, as we may infer, the vegetative 

 growth of a plant, and retard the flowering process. The association 

 between water and reproduction is specially discussed by Schimper 

 (p. 26) ; and he points out how highly instructive is the behaviour of 

 aquatic plants derived from terrestrial forms, which, whilst accom- 



