CONDUCTIVITY 



125 



show very clearly that in Difflugia the excitation following a 

 localized stimulus is dependent on the intensity of the stimu- 

 lus, and that according to the degree of this, the wave pro- 

 gresses in either stronger, more rapid and extended, or weaker, 

 slower and more limited manner. With the greater distance 



Fig. 17. 



Cyphoderia margaritacea. Result of localized mechanical stimulation at the end 

 of a long extended pseudopod. A, B, C— three successive stages. 



from the point of stimulation the excitation undergoes an increas- 

 ing decrement of its intensity and rapidity of conduction. Dif- 

 ferent species of Difflugia which I have investigated. Difflugia 

 lohostoma, urceolata, pyriformis, have shown a complete con- 



