54 



IRRITABILITY 



primary coil flows in the same direction. In consequence of this 

 there is a perceptible difference in the rapidity of the alteration 

 of the "make" and "break" shocks. (Figure 4.) 



Fig. 4. 



Course of induction shocks. 1 and 2 make and break of the primary current, 

 li and 2i make and break induction shocks. (After Hermann.) 



Now slowly reacting forms of living substance, such as certain 

 foraminifera, in which the extended pseudopods are stimulated 

 with single induction shocks, the break as well as the make 

 shocks are wholly without effect, as both take place far too quickly 

 for the slow responsivity of these organisms. I have made such 

 observations on various forms of foraminifera of the Red Sea, on 

 Orbitolites, Amphistegina and others. The movement of granules 

 in the pseudopods is not influenced by the induction shocks in the 

 least. It also continues without interruption when the pseudopods 

 are extended. Even with the strongest induction shocks at my 

 disposal I could not induce them to contract ; the faradic current, 



