182 life's beginning on the earth 



demonstrated particularly for the drops with broad pseu- 

 dopodia shown in Figure 72. The slow retraction or ex- 

 tension of these protrusions can only occur if the drop 

 respires. Poisons which arrest the respiration stop these 

 slow movements at once. (Fig. 73.) 



Another method of suppressing respiration is to prevent 

 access of air to the oil drop by keeping the water in which 

 it floats in a closed container. Presently all the oxygen of 

 the air is consumed. The oil-drop shrivels in such air-free 

 water, just as if poisons had been added. We may say that 

 the oil-drop has been suffocated. (The Amoeba also can 

 be suffocated, if it is kept in water from which all the dis- 

 solved air has been removed, and access of air prevented; 

 it will then disintegrate and die.) 



It certainly is worth while to reproduce in lifeless oil-drops 

 properties like respiration, poisoning, or suffocation — as 

 demonstrated directly or by the disappearance of a struc- 

 ture. All these properties are usually regarded as ex- 

 clusively pertaining to living animals. 



The oil-drop from fresh brain material can also be starved 

 like an animal. Dr. Telkes showed that the development 

 of this oil-drop does not occur if it is kept in pure water, 

 without the water-soluble brain constituents (the second 

 solution described on page 176). These brain constituents 

 play the role of food for the oil-drop. The material which 

 is burned up in respiration is not taken from the oil-drop 

 itself but from the dissolved material in the solution. Oil- 

 drops from fresh brain-material which float in pure water 

 have nothing to burn. Under these conditions they fail 

 to develop like a " well-nourished" oil-drop, with pseu- 

 dopodia. 



('). ARTIFICIAL CELLS AND POLITICS 



The oil-drops prepared from freshly extracted brain 

 material are of considerable importance in our attempt to 

 understand the complex machinery which serves for motion 



