EFFECT OF CLIMATIC CONDITIONS. 19 



In Table IV the results are arranged in the order of the loss in vital- 

 ity as shown by the second tests. However, a few words of explana- 

 tion will be necessary, especially concerning the loss at San Juan. In 

 the first place, the seeds were kept at San Juan only 131 days a during 

 the early part of the summer, while during the most critical period, 

 June 20 to November 6, they were in the botanical laboratory of the 

 University of Michigan. Those marked Mobile, Ala., were, during 

 the entire time, 262 days, under the influence of the warm, moist cli- 

 m;ite of the Gulf of Mexico. The seeds kept at other places can well 

 be compared with those from Mobile, the time being approximately 

 the same. The average loss as shown by the second tests was 3.35 

 times greater than the loss in the first test, which by calculation would 

 bring San Juan next below Mobile, with a loss of vital energy in the 

 seeds equal to 47.93 per cent. But more data are necessary before 

 such a gradation of injurious climatic influences can be established. 



Table IV, however, brings out another interesting point, as shown 

 by comparing the results of the first and second tests at San Juan and 

 Mobile. In the first test the loss in vitality of the seeds from Mobile 

 was 38.95 per cent, while the seeds returned from San Juan showed a 

 loss of only 14.31 per cent as compared with 71.98 and 21.39 per cent, 

 respectively, as shown in Table II. The degree to which the seeds 

 were injured while they were stored in San Juan was such that they 

 continued to deteriorate much more rapidly than the control sample. 

 This deterioration was most marked in the case of the pansy seed, the 

 germination of the first test being 20 per cent and that of the second 

 test only 6.5 per cent, showing a loss in vitality of 68.2 per cent and 

 87.7 per cent, respectively. Thus when seeds are once placed in con- 

 ditions unfavorable for the preservation of their vitality for a sufficient 

 length of time to cause some injury, this injury will always be mani- 

 fest and cause a premature death of the seeds even though they after- 

 wards be removed to more favorable conditions. 



Seeds of strong vitality can withstand greater changes in conditions 

 than seeds of low vitality without any marked deterioration. Through- 

 out these experiments a wide difference has been observed between 

 the "A" sweet corn and the "B" sweet corn. The original tests 

 made January 30, 1900, at the time the seeds were received, showed a 

 germination of 94 per cent for the " A" sample and 88 per cent for 

 the "B" sample of corn. The control tests, made in November, 1900, 

 showed a germination 0.5 per cent higher in each case; but the average 

 loss in vitality of the two samples of seed kept at the various places 

 was 12. 17 per cent for the "A" sample and 26. 10 per cent for the "B" 

 sample. As with the pansy and the phlox these samples showed that 



The number of days here given for San Juan is not absolutely correct. The time 

 was reckoned from the date the seeds were sent from the laboratory until they were 

 received in return. 



