KFFEC^T OK DEFINITE QUANTITIES OF MOISTURE. 48 



no water wiis iiddod. Howovor, a toniperature of •40'^ C. is sufticioiit 

 to injure man}' seeds, even thouoh the lil)erated water be permitted to 

 escape, as is shown in the tests of the onion, No. 1530 of the tal)le. 

 The o-reatest ininrv when air-dried seeds arc sealed in ])ottU'sand tiien 

 subjected to a hitrher temperature is duo to the increased humidity of 

 the confined air, as a result of the water liberated from the seeds. 



At Hrst [jflancc some of the conditions given in the ai)ove table ma}' 

 seem to be extreme and far beyond an}- normal conditions that would 

 1)0 encountered in the ordinary handling of seeds. This may seem to 

 be especially true with the seeds kept in the ])ottles with 8 cc. of 

 water where the additional amount of moisture absorbed gave rise, in 

 some of the seeds, to a water content of approximately 20 per cent. 

 Yet this need not be thought of as an exception, for such extreme 

 cases are often encountered in the commercial iiandling of seeds. 

 During the process of curing even more drastic treatment is not 

 infrequently met with. Pieters and Brow^n" have shown that the 

 common methods employed in the harvesting and curing of 1\hi pvd- 

 tciuh L. were such that the interior of the ricks reached a tempera- 

 ture of 130'^ to 140^ F. {iAA- to 60" C.) in less than sixteen hours, at 

 which temperature the vitality of the seed is greatly damaged and 

 fro([uently entirel}' destroyed. The interior of one rick reached a 

 temperature of 148^ F. i^WA'^ C.) in twenty hours, and the vitality 

 had decreased from 91 per cent to 3 per cent, as showni by the ger- 

 mination of samples taken simultaneousl}' from the top and from the 

 inside of the same rick. 



On the other hand, the extreme cases need not l)e considered. 

 Take, for example, the onion seed that was sealed in a bottle with 

 1 cc, of water and maintained at a temperature of 37^ to 40"^ C. The 

 increase in weight due to the water absorbed was 3.91 per cent, thus 

 giving a moisture content of 11.2 per cent and a complete destruction 

 of vitality. The cabbage seed, kept in the same bottle, had absorbed 

 a quantit}^ of water equivalent to 2.35 per cent of its original weight, 

 which, with the 5.90 per cent contained in the original sample, gave 

 8.25 per cent of water. This sample of seed germinated only 11 per 

 cent, having thus no economic value. In neither of these samples 

 was the amountof water present in the seeds greater than that ordi- 

 narily found in commercial samples. Moreover, the temperature was 

 much below that frequentl}^ met with in places where seeds are 

 offered for sale and likewise well within the limits of the maximum 

 temperature of our summer months, especially in the Southern 

 States. Take, by way of comparison, the maximum temperatures of 

 some of the places at which seeds were stored to determine the effect 

 of climate on vitalit}^, as shown in another part of this paper. During 



« Bulletin 19, Bureau of Plant Industry, U. S. Department of Agriculture, 1902. 



