266 VITALITY OF SEEDS. [BOOK n. 



and, therefore,, it cannot be these agents which have occa- 

 sionally preserved vegetable vitality in the embryo plant for 

 many years. 



The preservation of vitality in seeds depends upon the 

 stability of the chemical compounds of which they consist. 

 This appears to be the hinge upon which every thing turns. 

 Before a seed is quite ripe its elements are highly unstable 

 or liable to change, and the least alteration in the conditions 

 to which they may be exposed will cause them either to ger- 

 minate or perish. But when a seed is perfectly ripe its 

 elements become comparatively stable or indisposed to change, 

 and to induce germination is in proportion difficult, while 

 those alterations which are succeeded by death are slow in 

 taking effect. Dryness in all cases, and in some a perfect 

 exclusion of atmospheric air, are found to be the conditions 

 upon which the preservation of life in seeds mainly depends. 

 Some seeds will live for a long time if gathered ripe and pre- 

 served quite dry ; others will perish after a short time 

 although kept dry, and these demand the exclusion of air in 

 addition. Corn, Pulse, and, in general, farinaceous seeds, 

 belong to the former, while all oily seeds, and such as contain 

 much tannin, are to be classed in the latter series ; appa- 

 rently because of the great affinity of their compounds for 

 oxygen. This explains why, under the same circumstances, 

 one kind of seed will survive a voyage, and another dies. A 

 man buys Corn, Peas, Beans, Nuts, Acorns, and Holly- 

 berries, and sends them to the antipodes : the first three 

 and the last survive the voyage : the others invariably 

 perish. 



The mode of packing seeds is generally such as to render 

 this risk greater than it need be. Half dried seeds are placed 

 in half dry papers, and the whole are inclosed in a tin case 

 placed in the hold of a ship. There the temperature rises ; 

 the dampness present favours germination; growth com- 

 mences ; all the stable chemical compounds of the seeds are 

 suddenly converted into unstable principles, and as growth 

 cannot possibly go on, death ensues ; last follows decay. The 

 remedy is obvious. Great care in drying the seeds, and the 

 papers they are packed in, and free ventilation in a cool 



