Carbon Dioxide in Maturation, etc., of Seeds. 



621 



and it was found as the outcome of a number of experiments that when they 

 were sealed in the proportion of 40 to 50 seeds to 1200 c.c. of air the 

 following results were obtained: — (1) A partial pressure of C0 2 of 40-45 per 

 cent, was created in the flasks by the life processes of the seeds, and (2) 

 there was a marked prolongation in their period of vitality. 



In the following Table the results of two experiments are given. The 

 imported seeds, when received in this country, were necessarily some weeks 

 old. The temperature at which germination tests were conducted was 27° C. 

 in a thermostat : — 



Table XI. — Showing prolonged Dormancy of Hevea brasiliensis Seeds 

 sealed in flasks as described. Flasks opened after 50 days. A test 

 germination, begun at the time of receipt of the seeds, gave 40 per cent, 

 germinations. 



How kept during 50 days. 



Analysis of atmosphere on 

 opening flasks after 50 days. 



Percentage of 

 germinations after 



CO.. 



2 . 





60 days. 



Experiment 1 — 



50 seeds in air in 1200 c.c. sealed 

 flasks 



50 seeds in air in 1200 c.c. open flask 

 50 seeds in air in commercial packing 

 as sent from tropics 



per cent. 

 45 



per cent. 

 1 -3 



per cent. 



53 



per cent. 



40 (good plants) 









8 

 16 



Experiment 2 — 



20 seeds in air sealed in 500 c.c. flask 

 20 seeds in nitrogen sealed in 500 c.c. 

 flask 



20 seeds in air in 500 c.c. open flask 



40 

 41 



4-0 

 10 



■ 



56 

 58 



40 (good plants) 

 25 



o • . . i 



The first of the above experiments took place over the months of November 

 and December. The flasks were kept in a temperature varying from 10° to 

 15° C. 



The second experiment took place during December and January. The 

 flasks were kept in the laboratory, the temperature varying from 18° to 

 13° C. There was considerable internal pressure when the flasks were opened 

 in both experiments. 



In a third experiment the period during which the seeds were kept from 

 date of importation was prolonged to 90 days. The average temperature 

 was considerably higher, the months over which the experiment extended 

 being September, October, and November. In this case 10 per cent. 



