HEAT REQUIRED FOR GERMINATION. 49 



and 68° the seeds invariably came up the second day. At 69.8° 

 germination took place in less than a da}' — twenty-two hours. 

 This was the most rapid rate reached. At 77° the rate slightly 

 diminished, and at 82.4° only a small proportion of the seeds 

 sprouted, and those at the end of the third day. At 104° not a 

 single seed germinated. 



The lowest temperature at which the seed of the Cantaloup 

 melon germinated, was about 61.5° to 62.5°, more than nine days 

 being required at this heat. From 66° the period was nearly uni- 

 form up to 75°, being three days. From 77° to 82.5° it slightly in- 

 creased, as the seeds did not germinate till the fourth day, and 

 this period was maintained with little vai'iation up to 104°. At 

 105° one seed came up in ninety-four hours, that is, four days less 

 two hours." The mustard and melon were quoted as examples of 

 plants requiring, one a low, and the other a high temperature. 



" Many other species tried, exhibited the same rapid increase at 

 first, then uniformity during a long series of augmentations of 

 temperature, succeeded by longer periods until the upper limit was 

 reached. The seeds of Collomia coccinea offered a curious excep- 

 tion. They will germinate between 41° and 43°, but not readily 

 except between the narrow range of 48° to 62°. Above this the 

 heat becomes injurious to the species, and at 70° it took twentj'- 

 seven days, and with a greater heat the seeds did not germinate 

 at all." 



Mr. Hovey thought this statement a most interesting one. Cali- 

 fornia seeds do not generally come up except in a temperature of 

 about 43°, and at a few degrees above or below that point they do 

 not germinate freely, corroborating the statement as regards the 

 Collomia. He thought the principle established by these experi- 

 ments would appl}' to plants as well as to seeds. If azaleas were 

 placed in a temperature of 40° thej^ wbuld show no movement, but 

 plants in a heat of from QS^ to 80° had already done blooming. 

 You will find that the amount of the temperature above 32° will 

 produce nearly the same effect whether applied in two weeks, or 

 distributed over two months. 



The Chairman said that, admitting the correctness of Mr. 

 Hovey's concluding statement, the important question is whether 

 it is all the same to the plant. 



James Cruickshanks related an instance which came under his 

 observation in England, where a gentlemen was about to give a 



7 



