160 STUDIES ON RESPIRATION. XIX 



rate reaching a maximum of 200 per cent in 30 minutes after beginning 

 the exposure to the ether. This second rise undoubtedly masked 

 the earlier fall in experiments by the older methods, which did not 

 allow readings to be made at such short intervals. The rise is suc- 

 ceeded by a fall, so that after 78 minutes the rate was reduced to 60 

 per cent. The rate continued to dechne slowly after this. The 

 above figures represent the mean of ten typical experiments. 



With 7.3 per cent ether, the general effects are similar, A mini- 

 mum rate of 70 per cent of the normal was reached in 9 minutes, 

 and the respiration remained subnormal for 12 minutes. The suc- 

 ceeding rise was very rapid, and reached a maximum of 235 per cent 

 in 15 minutes. The rate then fell rapidly, reaching 60 per cent in 

 39 minutes. These data are the mean of six typical experiments. 



In order to determine if the observed preHminary fall was really 

 due to the action of the ether, and not to some experimental error 

 inherent in the method, the work was repeated, using the direct 

 indicator method as developed by Haas. The seeds were placed 

 in a Pyrex tube of the same dimensions as the standard buffer tubes 

 used for comparison, and the normal rate determined by adding meas- 

 ured quantities of tap water, containing phenolsulfonephthalein, 

 5 drops to 10 cc. The water was brought to the required pH value 

 by the addition of traces of NaOH. The tube was closed, and in- 

 verted several times, so as to mix the contents thoroughly. After 

 the time taken to change from pH 7.36 to 7.09 was noted, the seeds 

 were well rinsed with several changes of tap water. The ether was 

 made up with tap water and the indicator added. It was found that 

 the results were essentially the same. That is, a curve was obtained 

 showing three well malrked divisions: a preliminary fall, a rise, and 

 a final slower declension. It is thus reasonably certain that these 

 results are due to some specific action of the ether. 



The increase in rate followed by a fall was also observed by Thomas^ 

 in experiments on wheat but she does not describe a preliminary de- 

 pression. In regard to the latter the results recall those of Irwin* on 

 frog eggs and Fundulus embryos. In these cases Irwin found that the 

 first effect of ether, in certain concentrations, was a fall in the rate 



3 Thomas, H. S., /. Gen. Physiol. 1918-19, i, 203. . 

 ' Irwin, M., /. Gen. Physiol. 1918-19, i, 209. 



