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, also, the intensity of which I found quite unbearable, remained utterly without effect.[34] These two extreme cases, the nerve and the foraminifera, show plainly that the effect of a stimulus is not produced by the absolute rapidity of the increase of intensity, but is solely influenced by the relative rapidity of the same. [34] _Max Verworn_: “Untersuchungen über die polare Erregung der lebendigen Substanz durch den constanten Strom.” III Mitteilung, Pflügers Arch. Bd. 62, 1896. [Illustration: A B C Fig. 5.] A further point for consideration in the duration of an alteration in a vital condition in producing a stimulant action is the _length of time the stimulus remains after reaching its highest point_. In the forms of stimuli occurring in nature the duration of the alteration after reaching its highest level can vary considerably. The stimulus may remain indefinitely at a certain level, when this is once reached. (Figure 5, A.) The alteration likewise persists. This would be the case, for instance, with the changes of concentration in the transfer of an organism from fresh into sea water. The alteration can also, however, immediately after attaining its highest level, return, so that the original state is at once reestablished. (Figure 5, B and C.) Here it is a case of a quick deviation in the external vital conditions. A _sudden jar_ would be a case in point. Between these two extremes we have all variations in the duration of all natural and experimental forms of single stimuli.