Some Physical Properties oj Protoplasm 



247 



The average time for the anesthesia of Myxomycetes by carbon 

 dioxide, administered with an equal proportion of oxygen, is one 

 minute, with recovery in the same time. A proportion of three parts 

 carbon dioxide and one part oxygen produces anesthesia in half a 

 minute, and permits recovery within two minutes. The time for 

 both anesthesia and recovery varies with the concentration and 



Fig. 1. A Plasmodium anesthetized with carbon dioxide: left, the normal 

 protoplasm at the moment of reversal in flow; right, the anesthetized protoplasm. 

 In the latter the protoplasm is quiet and remains so for several minutes, fol- 

 lowed by a return to normal; note absence of any injury or observable pathologi- 

 cal change in the anesthetized protoplasm. 



method of application of the gas. A substantial dose quickly given 

 will put the Plasmodium under within twenty seconds, and may 

 delay recovery for from eight to ten minutes. As low a concentra- 

 tion as 10 per cent of carbon dioxide is sufficient to produce anes- 

 thesia for brief periods. 



Of general biological and medical interest are the unexpected 

 results that carbon dioxide proved to be the most successful anes- 

 thetic agent for Myxomycetes though that gas is one of the least 

 satisfactory for man; that ether, the most used among surgical 

 anesthetic agents, proved very unsatisfactory for slime molds; that 

 cyclopropane and chloroform are as successful in inducing the 

 anesthesia of very primitive forms of living matter as they are in 

 anesthetizing higher forms of life; and that ethylene, one of the 



