126 



IRRITABILITY 



formity in this respect. A great number of other fresh water and 

 marine rhizopods, the pseudopods of which I have used for anal- 

 ogous experiments, although differing in the manner of reaction 

 in regard to the extent and rapidity of the course of excitation, 

 manifest exactly the same fundamental principles. A very 



Fig. 18. 



Cyphoderia margaritacea. Result of localized mechanical 

 stimulation in the middle of a long extended pseudopod. 



favorable form is, for instance, the much smaller Cyphoderia 

 margaritacea, which is distinguished by a somewhat higher degree 

 of excitability and rapidity of reaction.^ The long straightly 

 extended pseudopods are thinner and more threadlike than those 



1 Max Verworn: "Die Bewegung der lebendigen Substanz. Eine vergleichend physi- 

 ologische Untersuchung der Contractionserscheinungen." Jena 1892. 



