428 



T. VOKOI. 



the specific gravity varying from 1.200 to 1.280 — is used. Accord- 

 ing to my experiment made some years ago the specific gravity of 

 nigari varies with the number of days passed after it has been 

 produced, a new one having a higher specific gravity than old one 

 with a dark colour and dirty sediments. This is probably due to 

 the fact that during standing the salt in solution gradually crystal- 

 h'ses out on the bottom of the containing vessel. Thus when a 

 liquor with a high specific gravity is required a good new nigari is 

 preferred, as for naked barley and wheat. The reason why I have 

 tried to use these instead of various salts which are obtainable from, 

 the apothecary and which could easily be managed to get any 

 required specific gravity is simply that the latter are generally too 

 costly for general use by small peasants. Our farmers have already 

 learned and tried the method and it is now widely practiced 

 especially for rice seeds either common salt solution or nigari 

 diluted with water being used for the purpose. 



Now the question is why does the "specific gravity method" 

 of selection give generally such good result Why did those 

 experimenters who selected the grains by their specific gravity 

 regardless of their weight give also good results when specific 

 gravity is not a measure of the quality of seed ? This question has. 

 now to be answered, and the main object of our experiments has 

 been to solve this important question. 



Certainly it is one thing to be used as a standard for the valuation 

 of quality, and another to be used as a medium of selection. As a 

 measure of quality, specific gravity is surely not to be relied upon as 

 scientifically accurate ; but as a medium for selection, it can be used 

 as sufficiently accurate for practical purposes though not scientifical- 

 ly so. And our experiments tend to show that at least for some 

 cereals " specific gravity method of selection " can be applied with 

 sufficient accuracy. 



As absolute weiglit has been clearly shown to be a sufficiently 

 correct measure of the quality of a seed, and as the quality of a seed 

 improves with the increase of its weight, the object of our experi- 

 ments has been first to find out whether the specific gravity has any 

 or no relation with the absolute weight of a seed. 



According to Schertler^^' the specific gravity of a seed increases 

 Avith its size except in the case of abnormally large grains, which 



(7) Schertler, die Anwendung des specifipchen Gewrichtes als Mittel zur Werthbestim- 

 mung der Kartoffeln, Ceiealieii und Hiilscnfruclite sowi'e des Saatgetreidcs, Wien 1873. 



