314 PROTOPLASM 



exactly similar appearances arise over the entire surface. 

 Moreover, it has been known for a long time back that the 

 formation of fine processes can also be effected by salt 

 solution over the whole surface of certain Amoebae ; processes, 

 that is to say, such as usually compose the posterior tuft. 

 The following observation, which I made casually upon 

 Amoeba proteus, is also evidence for the correctness of 

 the explanation here attempted of the formation of the 

 tuft. A specimen, which had been treated for a long time 

 with 0*05 per cent solution of caustic potash, suddenly 

 burst at a spot, as one frequently observes. Thereupon 

 the internal protoplasm flowed out, and the membrane-like 

 envelope shrank up together very much, at the same time 

 assuming the bristly appearance of the tuft over its whole 

 extent. As has been said, this observation seems to prove 

 for certain not only the existence of the tough membrane- 

 like enveloping layer, but also the great probability of my 

 explanation as to the formation of those fine processes or folds. 

 The bursting, here described, of the Amoeba, together with 

 the flowing out of the relatively fluid internal protoplasm, 

 may frequently be observed under the action of various 

 reagents, and also under a long-continued action of the con- 

 stant current ; on the other hand, a shrinking of the 

 enveloping layer in its whole extent, which has just been 

 described, I only saw once in this manner. 



Hence if we are constrained to admit the existence of a 

 tough, membranous layer on the surface of numerous 

 Amoebae, the question is then raised, in what way this layer 

 becomes liquefied at the anterior end, or rather at the spots 

 where the pseudopodia develop ; for there can be no doubt 

 that it must be liquefied. In this process may be traced 

 a result of external local stimuli which concern the 

 Amoeba. That such stimuli must in the last instance 

 be the cause of the movements, and of the development 

 of pseudopodia, is beyond doubt. Nevertheless I do not 

 think that the liquefaction is in direct connection with this 

 fact, but that the outflow of enchylema, which is produced 

 by the bursting of some of the alveoli, is the primary cause 

 of the liquefaction of the superficial layer. This is, in fact, 



