STIMULI AND THEIR ACTIONS 473 



chloroform, or other chemical substances, in a few seconds it draws 

 itself together into a ball (Fig. 243, JB), and thus gives the im- 

 pression of intense excitation of contraction. In the course of a 

 longer, constant action of the stimulus the protoplasmic body 

 begins to undergo granular disintegration from the periphery 

 (Fig. 243, C). If, however, the chemical stimulus be allowed to 

 act in greater intensity upon the resting, extended body, the stage 

 of excitation has no time for its development. The body begins 

 immediately, without first contracting into a ball, to undergo 

 granular disintegration in the form which it had at the moment 

 of stimulation (Fig. 244, B). Here death appears immediately as 

 a result of stimulation, while the other stages of the reaction have 

 not time to develop externally. The same is seen in galvanic 

 stimulation. If Actinosph cerium be stimulated by feeble galvanic 

 currents, the typical phenomena of excitation of contraction appear 

 at the anode. The protoplasm of the pseudopodia forms small 

 globules and spindles, and flows centripetally, until the pseudopodia 



FIG. 244. Pelomyxa palustris. A, Creeping; B, undergoing granular disintegration as a result of 

 strong chemical stimulation. 



are wholly retracted. If, however, a strong galvanic current be 

 applied suddenly, the protoplasm has not time to contract, but 

 immediately undergoes disintegration at the anode. 



Granular disintegration of protoplasm as a result of supramaximal 

 stimulation is a valuable aid when, as e.g., in stimulation by galvanic 

 currents, the localisation of the excitation is to be determined in 

 objects in which there is no other distinctly visible expression of it. 

 In such cases it is only necessary to employ supramaximal currents, 

 and the place of excitation is recognised at once in the granular 

 disintegration of the protoplasm. Of course this is possible only in 

 forms of living substance which, at the moment of death, show 

 granular disintegration. There are many forms of cells, especially 

 those that are provided with a solid wall, which in dying do not 

 pass into granular disintegration at all. Yeast-cells, e.g., can be 

 killed in various ways by over-stimulation without any disintegra- 

 tion of the body. Their death is indicated only indirectly, by loss 

 of the power of splitting grape-sugar into carbonic acid and alcohol. 

 But we need not here go more in detail into the different forms in 



