32 



COMPARATIVE PHYSIOLOGY 



cilium, as in 

 mechanism. 



muscle, is an essential part of the contractile 

 The same appears to be the case with amoeboid 



Velocity curves ob- 

 tained from Type B 

 amoebae in a medium 

 acidified with citric 

 or tartaric acids.. Th« 

 citric curve marked 



thus □ -; was 



obtained with car- 

 bonate-free sea water. 



HCl ....+ 



Citric O and Q 



Tartaric ... ^ 



pH&O 



Four velocity 

 curves obtained suc- 

 cessively from tlie 

 same Type B amoeba,. 

 Each curve taken 

 with a fresh acid, after 

 recovery. in "outside 

 sea water," 



Curve 1 with HCl. 

 „ 2 ,. Citric. 

 ,, 3 „ HiSO« 

 ,, 4 ,, Tartaric. 



pH6*0 7-0 60 5-0 



Fig. II. — Relation of hydrogen ion concentration to the velocity of 

 Amceboid movement (after Pantin). 



movement. Bethe, Harvey, and others have used dyes which 

 stain the living cells and are themselves indicators of hydrogen 



