ACTION OF ANESTHETICS 81 



Gustafson * found that Aspergillus niger, subjected to the 

 action of ether, acetone, or formaldehyde, exhibits an increase 

 in its respiratory activity followed by a decrease. The use of 

 caffeine in saturated solution similarly brings about an increase 

 followed by a decrease whilst a *5 per cent solution results in a 

 decrease of respiration intensity. 



Similar results were found by Brooks \ to obtain in the 

 case of Bacillus subttlts, for which plant ether is toxic in low, 

 037 to i -i per cent, and in high, 3-65 to 7*3 per cent, con- 

 centration. In strengths intermediate to these the drug acts 

 as a stimulant to growth. Further, the action of ether varies 

 according to the presence or absence of other substances : thus 

 whilst the respiratory activity may be fifty times as great as 

 the normal under the action of a 7*5 per cent solution of ether, 

 this high intensity is considerably reduced if -85 per cent of 

 sodium chloride be added. 



According to Haas,J small doses of anaesthetics are with- 

 out result in the respiration of Laminaria y doses sufficiently 

 large to produce a measurable result bring about a prolonged 

 increase in respiration, whilst strong doses result in an initial 

 increase followed by a decrease ultimately to zero. In no 

 experiment was it found that the initial effect of an anaesthetic 

 was a lowering of the respiration intensity from which it is 

 concluded that the state of anaesthesia is not brought about by 

 the lowering of the respiration. It is clear from these results 

 that in general anaesthetics have a twofold action : a small dose 

 is a stimulant, a large dose is a narcotic. And this is true 

 not only for respiration but also for other expressions of plant 

 activity such as the circulation of protoplasm within the cell. 



THE CONDITIONING FACTORS. 



It will be obvious from the foregoing general consideration 

 that the intensity of respiration is dependent on the interaction 

 of various conditioning facts the more conspicuous of which 

 may now be examined. 



TEMPERATURE. In general terms an increase in tempera- 

 ture results in an increase in the respiratory activity until death 



* Gustafson : " Journ. Gen. Physiol.," 1909, I, 181. 

 t Brooks: Id., 1909, I, 193. 

 Haas : " Bot. Gaz.," 1919, 67, 377. 

 VOL. II. 6 



