42 THE VITALITY AND TERMINATION OF SEEDS. 



per cent in 30 days, while the average increase in weight during the 40 

 days was only 0.91 per cent. These results show that if seeds are once 

 carefully and thoroughly dried, they will remain so; that is, if kept in 

 a comparatively dry room. This is an important factor in the preser- 

 vation of vitality, as is borne out in the results of the germination 

 tests. Later experiments were made with very similar results, and an 

 analogous method of treatment promises to be of much value as a 

 preliminary handling of seeds. It is not definitely known to what this 

 stronger vitality is due, whether it be simply to the effect of the dry- 

 ing or to some process of chemical transformation which makes the 

 seeds more viable. These results are now under consideration and will 

 be reported at some future time. 



The table also shows in a very striking degree the decrease in the 

 number of germinable seeds with an increase in the moisture and 

 temperature. The amount of moisture absorbed by the seeds, with a 

 limited amount present in the bottles, was inversely proportional to the 

 temperature. At the higher temperatures the inclosed air held a larger 

 portion as water vapor; however, there was a greater deterioration in 

 vitality. Where the seeds were kept outdoors at the low temperatures 

 (21.6 to 8.9 C.) of the winter months, no injury was apparent 

 except where 3 cc. of water was added, and then only the onion seed 

 was affected. This sample of seed had absorbed a quantity of water 

 equal to 10.38 per cent of the original weight, which together with 

 the original water content (6.41 per cent of the original sample) made 

 17.88 per cent of moisture in the seed. Practically the same results 

 were obtained with the seeds kept in a fruit cellar at a temperature of 

 10 to 13 C. The samples of this series, in the open bottles, were 

 also injured, as has been pointed out. With the samples that were 

 stored in the dark room and in the herbarium room, the injury was 

 more marked as a result of the higher temperature; but even here the 

 seeds in the bottles which contained 0.5 cc. of free water deteriorated 

 very little. The injury was confined to the onion seed, which showed 

 a slight retardation in germination. Where 1 cc. , 2 cc. , and 3 cc. of 

 water were added, vitality in some instances was likewise remarkably 

 well preserved. The lettuce, tomato, and peas gave no indications of 

 any deterioration save in the bottles containing 3 cc. of water. Here 

 the lettuce and peas were permanently injured, while the tomato seeds 

 suffered only sufficiently to cause a delay in the rapidity with which 

 they germinated. The cabbage seed was retarded with 2 cc. and a 

 lowering of the final percentage of germination with 3 cc. of water. 

 The onion seed, being very sensitive to these unfavorable conditions, 

 deteriorated very greatly, being practically worthless where 3 cc. of 

 water were added. A brief study of the table will readily show that 

 many seeds were killed at the still higher temperatures of 30 to 32 

 C. and 37 to 40 C. The onion seed was slightly injured even where 



