GERMINATION OF SEEDS. 6oi 



analysed and the seeds tested in the first case. In the first 

 experiment the composition of the air had been practically 

 unchanged ; every seed germinated. In the second some 

 oxygen had been absorbed and some carbon-dioxide formed, 

 but the amount was small. In a third experiment twenty 

 peas iyPis2un ?) were introduced into a test-tube filled with 

 mercury, and inverted over this liquid. No gas was noticed 

 at the beginning or end of the experiment. After 4*5 

 years, ten peas were placed to germinate ; eight developed 

 perfectly, two refused. At the end of ten years and three 

 months the remainder were removed ; two germinated 

 normally, two abnormally, and six not at all. Thus peas 

 remained more than ten years in mercury-vapour of feeble 

 tension without respiring, and yet preserved ' vitality ' to a 

 certain extent. For the study of this question Ewart placed 

 seeds in corked bottles with an open erect tube containing 

 clean pieces of sodium ; the tube was then hermetically 

 sealed The atmosphere soon consisted of hydrogen and 

 nitrogen. After three and five weeks the seeds were tested. 

 Resistance, which was considerable, varied with the species. 

 This experiment is also of interest, since it measures the 

 resistance of the seeds employed to desiccation. 



Van Tieghem and Bonnier (20) have obtained results 

 discordant with those mentioned above. Samples of seeds 

 were divided into three equal parts, each having the same 

 number of seeds of the same species. One lot was placed 

 in a cardboard box, into the interior of which air had free 

 access ; the second was placed in a glass tube full of air, 

 which was then carefully corked and submerged under 

 paraffin at the corked end : the third was put into a test-tube 

 full of mercury which was then filled with carbon-dioxide. 

 The seeds had been previously weighed. Each tube was 

 submitted to like conditions for two years. All the seeds 

 left in the open air had increased in weight by the close of 

 this period ; those in closed air had done so very slightly, 

 whereas those in carbon-dioxide had not altered their weight. 

 Germinating power was highest in the seeds left in the open 

 air, much less in those kept in the closed air, whereas those 

 previously in carbon-dioxide failed to germinate in every 



