248 The Structure of Protoplasm 



newer and best anesthetics for man, had no observable effect what- 

 ever on shme molds."" Ethylene not only failed to produce anesthesia 

 in slime molds, but it stimulated their growth, an unexpected result 

 which may be due to increased respiration. 



That feature of the anesthesia of slime mold protoplasm by 

 carbon dioxide, cyclopropane, and chloroform which is of chief 

 interest to us at the moment is the instantaneous cessation of 

 streaming. There is little warning, occasionally a momentary tremor, 

 and then a sudden and complete stopping of flow. On removal of the 

 anesthetic agent there is resumption of normal activity, with no 

 observable damage. 



It is only necessary to observe the sudden cessation of proto- 

 plasmic movement in a slime mold due to the application of a suit- 

 able anesthetic agent to be convinced that the protoplasm has under- 

 gone a pronounced change in its physical as well as its physiological 

 state, yet no change is evident other than a stopping of flow. 



The instantaneous cessation of protoplasmic streaming caused 

 by carbon dioxide appeared to involve a setting or gelatinization of 

 the protoplasm. It also seemed likely that the failure of other 

 anesthetic agents to put a sudden stop to protoplasmic streaming 

 was an indication that no gelation had taken place, but there was 

 no direct proof of either deduction. 



By means of an ingenious technique involving the application of 

 pressure, Kamiya is able to oppose and control protoplasmic flow 

 (pp. 205, 206) . If protoplasm is quiet, due to anesthesia, pressure 

 externally applied should cause it to move if it is in a liquid state, 

 and fail to move it if it is firm. Such proved to be the case. Proto- 

 plasm under ether, which produces only partial anesthesia of slime 

 molds, is readily moved by externally applied pressure, whereas 

 protoplasm under carbon dioxide cannot be made to flow by pres- 

 sure. Obviously then, under carbon dioxide the protoplasm is firm; 

 under ether it is fluid. 



The foregoing facts form the basis of a theory of anesthesia, 

 applicable to those cases where suspended animation is brought 

 about quickly, as with carbon dioxide, cyclopropane, and chloro- 

 form when applied to slime mold protoplasm. The theory states that 

 anesthesia is due to the thixotropic setting of protoplasm. In the 

 case of higher vertebrates only nerves would be affected, whereas, 



' Anesthesiology, 2, 300. 1941. 



