With the greater distance from the point of stimulation the excitation undergoes an increasing decrement of its intensity and rapidity of conduction. Different species of _Difflugia_ which I have investigated, _Difflugia lobostoma_, _urceolata_, _pyriformis_, have shown a complete conformity in this respect. A great number of other fresh water and marine rhizopods, the pseudopods of which I have used for analogous 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 favorable form is, for instance, the much smaller _Cyphoderia margaritacea_, which is distinguished by a somewhat higher degree of excitability and rapidity of reaction.[81] The long straightly extended pseudopods are thinner and more threadlike than those 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, _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. [81] _Max Verworn_: “Die Bewegung der lebendigen Substanz. Eine vergleichend physiologische Untersuchung der Contractionserscheinungen.” Jena 1892. [Illustration: Fig. 17. _Cyphoderia margaritacea._ Result of localized mechanical stimulation at the end of a long extended pseudopod. A, B, C--three successive stages.] [Illustration: Fig. 18. _Cyphoderia margaritacea._ Result of localized mechanical stimulation in the middle of a long extended pseudopod.] [Illustration: Fig. 19. A pseudopod 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. ]