FRUITS AND SEEDS 251 



Seeds which have once been soaked and have then dried up 

 again will absorb water much more rapidly the second time, 

 but the testa is no longer the same. The increase of the seed 

 during germination may amount to 100 per cent, of its 

 volume, and this means that the testa becomes enormously 

 stretched. If it dries up, the testa shrinks again, and cracks 

 in innumerable places. When the seed becomes moistened 

 again, air and water will have a freer access to the tissues, 

 and the reserve material will become more rapidly dissolved. 

 It will, however, also pass more readily through the cell-walls 

 to the outside, and thus be lost to the embryo. 



We see, therefore, that the swelling of seeds previous to the 

 sowing can only be advantageous if we can protect the sown 

 seeds from drought. If this is not possible, then it would be 

 better to leave the seeds to tliemselves. This rule, that vegetative 

 processes should only be accelerated by copious water supply, 

 if it is possible to continue such a supply, applies also to the 

 third stage of germination, and to all stages in the development 

 of vegetative organs. A plant which has been well watered 

 from its youth will give off more water from its leaves than a 

 plant of the same species, and with the same amount of leaf 

 surface, but which has always received only a moderate supply 

 of water. The former will, therefore, fade, and ultimately be 

 injured, under conditions under which a plant used to a smaller 

 water supply and less transpiration can thrive very well. 

 Hence it is that we find that luxurious lawns will suffer 

 more than meagre ones, and luxurious pot-plants more than 

 their small-leaved relations. 



It is an agricultural rather than a horticultural practice in 

 some cases to manure the seeds, because it is believed that a 

 stronger seedling would be developed. For this purpose the 

 seeds are either coated with nutritive material or allowed to 

 swell in a solution of concentrated salts. Such a proceeding, 

 where it is not actually harmful, is at least useless. Experi- 

 ments with turnips, wliich can surely stand a lot in the way 

 of manures, have shown that ammonium or potassium sulphate, 

 even at a concentration of only 0.5 per cent., is deleterious to 

 germination. Cereals and leguminous plants are also not in 

 the least benefited and, indeed, germinate best in distilled 



