CONDUCTIVITY 



137 



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, 



y 



f 



Fig. 19. 



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

 6— Severed by a cross section near tlie end. 6-/— Five successive stages 

 of the effect 6-<f— Tlie pseudopod retracts by centripetal flowing of tlie 

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

 and /—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. 



