178 STUDIES ON RESPIRATION. I 



is that the result depends in most cases on the length of the experi- 

 ment. This is due to the fact that under the influence of the anes- 

 thetic the rate of respiration constantly changes. In the older 

 experiments this was overlooked and the discrepancies in the results 

 are doubtless due in large measure to- this circumstance. It is impor- 

 tant to be able to determine the rate of respiration at intervals of 

 5 or 10 minutes, or even less, as is possible by the method employed in 

 these studies. 



All of the plants studied in the writer's laboratory (including rep- 

 resentatives of bacteria, higher fungi, algae, and flowering plants) 

 agree in their behavior toward anesthetics. While lower concen- 

 trations produce no effect on respiration, higher concentrations cause 

 a rise followed by a fall: In general the rise of respiration appears 

 to be associated with reversible anesthesia while the fall below the 

 normal rate indicates irreversible toxic effects, at least if it goes much 

 below the normal. 



It is evident that these results are directly opposed to the theory 

 of Verworn. 



The results obtained by Miss Irwin upon animals are likewise not 

 in agreement with Verworn's doctrines, for although they show that 

 anesthetics may produce a temporary decrease of respiration, which 

 cannot be wholly explained on the ground of cessation of movement, 

 this decrease is much too small to produce anesthesia. 



On the other hand Miss Irwin's observations are interesting as 

 showing an apparent difference between animals and plants in their 

 behavior toward anesthetics, in that the temporary decrease followed 

 by an increase which is found in animals does not occur in plants. 

 If this should prove to be generally true, it is significant. 



The facts developed in these studies are of considerable interest 

 but it seems wiser to defer their interpretation until more infor- 

 mation is available. They offer suggestions for further attacks upon 

 the problem and have an important bearing on the theory of anes- 

 thesia. These investigations are being continued and it is expected 

 that additional results will be forthcoming in the near future. 



It may be added that throughout these articles the term respira- 

 tion is used as meaning oxidative processes which furnish energy, be- 

 ginning with the taking up of Oo and ending with the production of 



