140 STUDIES IN ELECTRO-PHYSIOLOGY: 



disturbance, but by reason of its high resistance would tend 

 to stop movement after a short time. In some cases 

 protoplasm can be almost entirely dried up, but remains 

 capable of renewing its movement when again moistened- 

 Its electrical activity and especially capacity is depen- 

 dent upon the presence of conductive moisture, and when 

 not so moistened it would become inert. That dilute salt 

 solution and very dilute alkalies stimulate the movements 

 temporarily by lowering internal resistance is what might 

 reasonably be expected. As, however, there would be 

 some alteration of the chemical composition of the cell- 

 contents the efficiency of the cell would no doubt be ulti- 

 mately impaired. Obviously also acids or strong alkalies 

 would permanently stop the movements by causing 

 diffusion ; ether and chloroform, as is well known, interfere 

 with conduction, and, moreover, I am quite sure that the 

 least trace of tincture of nux vomica would be fatal.* 



That movement is suspended in an atmosphere of 

 hydrogen or carbonic acid calls for no explanation, but the 

 fact that complete withdrawal of oxygen will, after a time, 

 kill protoplasm is a strong argument in favour of the 

 hypothesis that movement is due to electrical action. 



(3) Electrical. Weak currents, by supplementing the 

 natural energy of the cell, stimulate the movement, but 

 strong currents paralyse the protoplasm, or by disrupting 

 its electrical structure cause it to revert to its original 

 shape when at rest. 



In considering the theoretical solution I have offered 

 of amoeboid movement, it is as well to bear in mind that 

 although the chemical composition of the dead amoeba can 

 be resolved by analysis, such is not the case with the living 

 amoeba, in which, in all probability, these chemical sub- 

 stances are represented by their groups of ions. If that i s 

 so it can readily be imagined that, with a constant intake of 

 * See experiment with begonia (p. 159). 



