REST PERIOD STUDIES WITH SEEDS 13 



A sample of each species was planted immediately after it was 

 collected, while another sample was placed in the laboratory to become 

 air-dry, on the surface at least, when it also was planted. The drying 

 process usually lasted for about thirty days, so that the two plantings 

 of seeds of each species followed each other at intervals of about one 

 month. 



The idea in view in making these two plantings was to find which 

 species are able to germinate immediately upon ripening, and which 

 require a further period of ripening or development before germina- 

 tion can take place. It was assumed that seeds at maturity contain 

 perhaps a greater amount of moisture than at any time thereafter 

 until planted. Allowing them to become air-dry before planting might 

 introduce a serious external hindrance to growth in the form of a 

 hard seed coat. Therefore, it was hoped to find from these plant- 

 ings : first, whether the seeds had a natural rest period that is, failed 

 to grow at maturity and second, whether the drying out process, such 

 as would take place in ordinary storage, might not prevent germina- 

 tion on account of a hardened seed coat, or because the rest period 

 sets in later than at maturity. 



All plantings of seeds were made in moist sand on a greenhouse 

 bench. The seed bed was four or five inches deep and was kept moist 

 by frequent sprinklings. All outside conditions, such as light, heat 

 and moisture were the same for both the first and second plantings. 



The collection made in 1911 consisted of 122 species of seeds. 

 The first were planted on May 20 and plantings continued as seeds 

 were collected, throughout June, July, August, and up until Septem- 

 ber 14. For the most part the seeds were from herbaceous plants, 

 including annuals, biennials, and perennials. However, there were 

 a goodly number of woody forms included in the list. 



Table 6 shows the entire list of seeds, together with the treat- 

 ments and results. For convenience in studying the behavior of the 

 species under treatment, as regards their botanical relationships, they 

 are arranged in the table by natural orders. The first column of 

 figures shows the dates on which the various species were collected. 

 An effort was made to plant one sample on the date collected, the 

 second sample of the same species being planted when sufficiently 

 dry, which as already stated, was usually after about thirty days. 

 Columns two and three, under the headings "mature seeds" and "dry 

 seeds," show the number of days elapsing in each case before the 

 seeds began to germinate. The last two columns of figures show the 

 percentage of mature and dried seeds that sprouted. In some in- 

 stances the dried seeds, and sometimes even the newly ripened seeds, 

 failed to make any growth up to the time when observations ceased, 

 on October 15. 



