40 THE VITALITY AND GERMINATION OF SEEDS. 



The foregoing table, showing the conditions under which the seeds 

 were kept, has been made quite complete. Aside from the final per- 

 centages of germination, the percentages of germination after a defi- 

 nite number of hours have likewise been given, the latter being better 

 expressed as germinative energy. The germinative energy, as has been 

 previously stated, is an important factor in determining the potential 

 energy of a seed. This is quite clearly shown in many of the germi- 

 nation tests recorded in the above table. The preliminary results show 

 a marked contrast as a result of the different kinds of treatment, while 

 the final results reveal nothing more than the regular degree of varia- 

 tion usually met with in testing seeds. Of the five species of seeds, the 

 onion has yielded the most striking variations in the earlier stages of 

 germination. Take, for example, No. 1535, the sample that was kept 

 in an open bottle in the fruit cellar. The moisture absorbed was suffi- 

 cient to cause a chemical transformation, which injured the vitality of 

 the seed and consequently caused a retardation in germination. No. 

 1539, the onion seed from the incubator maintained at a temperature 

 of 37 to 40 C., germinated only 16.5 per cent in 77 hours, while 

 the final percentage of germination was 95.5 per cent. Onion seeds 

 Nos. 1532 and 1533 germinated in 77 hours 18.5 and 2.5 per cent 

 respectively, while the final germination of the former was 93.5 per 

 cent and of the latter 96 per cent. All of these tests gave final per- 

 centages of germination somewhat higher than the mean of the control 

 samples. But the germination was considerably retarded, the control 

 samples having germinated 29.5 per cent during the first 77 hours. 

 These retardations in germination must be due to a lowering of vitalit}^, 

 as a more careful study of the table will show, and not to any excessive 

 drying that may have taken place during the time of treatment. 

 Numerous other examples are to be found in the table, some even 

 more striking than those mentioned, but it is not deemed necessarj' 

 that they all be pointed out and discussed here. 



The table also shows the results of the various weighings made of all 

 of the different samples which were kept in closed bottles. With but 

 very few exceptions there was an increase in weight, which increase 

 was quite marked in all cases where free water was introduced. The air- 

 dried seeds that were sealed in bottles without the introduction of free 

 water all increased slightly in weight, with the exception of the peas, 

 which showed a slight decrease in weight. It has been observed that 

 the absolute loss in the weight of the peas was slightly greater than 

 the total gain in the four other samples of seed. This, however, is 

 not of sufficient uniformity throughout to fully justify the conclusion 

 that cabbage, lettuce, onion, and tomato seed have a greater affinity for 

 water than peas, and that the former robbed the latter of a portion of 

 their water content. Yet a portion of the increased weight of the 

 cabbage, lettuce, onion, and tomato seed is probably best accounted 



