RESPIRATION OF SEEDS. 77 



Carrot. Of carrot seed, 10 grams were allowed to absorb during 

 175 hours an additional 10.25 per cent of water. In one year 27 cc. of 

 carbon dioxid were produced, giving a concentration of carbon dioxid 

 of nearly 12 per cent. The deterioration in vitality was from 84 to 

 per cent, as compared with the control. 



Lettuce. Of air-dried lettuce seed, 10 grams were allowed to absorb 

 an additional 8.87 per cent of water. During the experiment 19.5 cc. 

 of carbon dioxid were formed, an equivalent of approximately 10 per 

 cent of the original volume of the inclosed air. These seeds were all 

 killed. The control sample germinated 94 per cent. 



Onion.. Of air-dried onion seed, 10 grams were allowed to absorb 

 an additional 10.11 per cent of water. The seed gave off 26.5 cc. of 

 carbon dioxid during the experiment and deteriorated in vitality from 

 97 to per cent. 



A bottle containing 4 cc. of water was also sealed at the same time 

 and served as a check for the other analyses. A sample of air taken 

 from this bottle gave the same results as the original air sample. 



It is a matter of much regret that no analyses could be made of the 

 air from the bottles which contained the check samples. These bottles 

 contained the same weight of air-dried seeds as was used for the 

 experiments. Unfortunately the seals on these bottles had become 

 dry and admitted of an exchange of gases, so that the results were not 

 reliable. 



Another series of experiments consisted in keeping onion seeds in 

 sealed bottles for 1 year and 13 days, with the following results: 



(a) Fifty grams of air-dried seed were sealed, in air, in a bottle of 

 500 cc. capacity. There was an increase in the weight of the seeds of 

 0.1091 gram slightly more than 0.2 per cent. An analysis of the 

 inclosed gas gave: 



Per cent. 



Oxygen 12. 27 



Nitrogen 85. 87 



Carbon dioxid 1. 86 



() Fifty grams of air-dried seed were sealed, in air, in a 500 cc. 

 bottle, with 4 cc. of water in a small test tube at the bottom of the 

 bottle. Nearly all of the water was absorbed by the seeds, there 

 being an increase in weight of 3.6475 grams, or 7.3 per cent. The 

 composition of the inclosed air was: 



Per cent. 



Oxygen None 



Nitrogen 86. 65 



Carbon dioxid 13. 35 



The oxygen had all been consumed and the seeds were all dead. 



(c) Fifty grams of onion seed were sealed in a 500 cc. bottle, in a 



