CHAPTER XI 



ANESTHESIA AND NARCOSIS 



We are familiar with the power of anesthetics in restraining 

 the activity of the central nervous system, especially the reflex 

 and voluntary activities which they affect in lower concentrations 

 than those affecting other organs. Since the higher animals die 

 as soon as the activity of the respiratory center ceases, and under 

 artificial respiration as soon as the heart beat ceases, it is possible 

 in the intact animal to study the effects of anesthetics only on 

 certain nerve synapses, i. e., structures whose threshold of 

 anesthesia is lower than that of the heart mechanism. Anesthetics 

 in higher concentrations suspend the activity of cells and of 

 animals lacking a nervous system. Claude Bernard showed that 

 ether may prevent the movement of the leaves of Mimosa, a 

 sensitive plant. 



Overton (1901) observed that vertebrates, insects, and ento- 

 mostraca (small Crustacea) require practically the same concen- 

 tration of anesthetic (or the same vapor pressure of volatile 

 anesthetic) in order to suspend reflex excitability, whereas cer- 

 tain groups of worms require double this concentration. Protozoa 

 and plants require, in order to suspend their activities, six times 

 the concentration of anesthetic required to anesthetize verte- 

 brates. From Warburg's data, the concentration of anesthetic 

 necessary to reduce the oxidation of goose erythrocytes 30-70 

 per cent is about six times the concentration necessary to anesthe- 

 tize vertebrates, although some variation in regard to individual 

 anesthetics is apparent. Slight discrepancies might be due to the 

 fact that the anesthesia data were taken by Overton on samples 

 of anesthetic of a lower degree of purity than those used by 

 Warburg to reduce oxidation. It follows from this that protozoan 

 and plant cells react to anesthetics, not like nerve synapses but like 

 mammalian cells. According to Winterstein (1914), however, 

 narcosis of frog's spinal cord may either decrease or increase 

 oxidation. 2 is necessary for complete recovery. 



