ON THE " SALT WAT!:R SELECTION " METHOD OF SEEDS. 431 



On the other hand in the case of wheat and naked barley both 

 destitute of any husk their specific gravities do not show a regular 

 relation with the weights as in the case of rice and barley. 



These facts naturally suggest that light and porous husk has a 

 great influence upon the relation of weight and specific gravity. The 

 husk of rice and barley is formed before the development of seed 

 and the development of seed has little influence upon that of the 

 husk ; and the weight of the latter must have great influence upon 

 the specific gravity of the gra'n. There must be a great difference 

 in their specific gravity, according as the seed is well developed 

 and fills the inside of the husk, or is little developed and lies loosely 

 within the husk. As the husk is light and porous enclosing within 

 it a large quantity of air, its specific gravity is very small — smaller 

 than that of water — and if it be comparatively well developed it will 

 naturally decrease the specific gravity of a grain. Moreover when 

 the space between the husk and the seed be wide apart and 

 encloses a large quantity of air it w ill lessen the specific gravity of 

 the whole. If this be so, it is no wonder that in the case of rice and 

 barley, grains which are covered with light and porous husks, their 

 specific gravities should have a regular relation to their weight. 

 The results obtained by Ando on the absolute and percentage 

 weight of the husk are shown in the following table, the specimens 

 examined being in each case those used for the determination of their 

 specific gravities : — 



RICE; SORT, SMIRATAMA. 



\Veight of a 

 grain, mgr. 



Weight c)t 50 

 grains, nigi'. 



Sp. gr. 



Weight of husk, 

 mgr. 



Per cent of liu^k. 



Over 32 



1649.6 



1. 224 1 



272.7 



if'-53 



28—32 



1521.0 



1.21 5 1 



247.5 



16.93 



24— 28 



1325.8 



1. 181 1 



2258 



17-03 



20—24 



1 1 10.2 



1.120) 



200 7 



iSoS 



ISelow 20 



847.4 



o.gO 1 2 



176.1 



20.78 



