CONDUCTIVITY 



127 



of Difflugia and show upon stimulation as a result of their local 

 excitation a simple contraction into clumps of the stimulated 

 protoplasm without the characteristic differentiation of that of 

 Difflugia. (Figure 17.) In the case of the marine rhizopods, 



f 



Fig. 19. 



A pseqdopod of Orbitolites complanatus (cf. Fig. 7). a In normal condition. 

 b Severed by a cross section near the end. b-f Five successive stages 

 of the effect, b-d The pseudopod retracts by centripetal flowing of the 

 protoplasm contracted in the shape of microscopic balls and spindles, e 

 and f The pseudopod begins to extend again. The centripetal flowing 

 balls and spindles begin to disappear. 



Orbitolites (Figure 19), Amphistegina, etc., which I investigated 

 at the Red Sea, the conduction of excitation takes place also as 

 in Difflugia with a decrement of intensity and rapidity becoming 

 larger with the distance from the point of stimulation until the 

 wave of excitation is obliterated. 



