Dissection and Injection Studies on Amceba. 



67 



If the "basic" dye be relatively nontoxic its injection results 

 in a coagulated area which is localized as a colored lump of inert 

 material. This lump is carried about in the protoplasmic currents. 

 The color gradually diffuses out of the lump and stains many of 

 the cytoplasmic inclusions in the Amceba. 



Dissection indicates that the granular endosarc is capable of 

 easily reverting from a fluid to a solid state and vice versa. 

 Peripheral to the endosarc is a hyaline liquid zone, the ectosarc, 

 which is bounded externally by a very thin, extensible, pellicle. 

 The extosarc can be enlarged by a hyaline liquid extruded from 

 the endosarc. 



In the formation of a pseudopod a localized area of the pellicle 

 softens. The accumulation of liquid in the ectosarc immediately 

 under this area produces a bulge. The more jellied endosarc at 

 the base of the bulge liquefies and a liquid suspension of granules 

 streams into the bulge and up to its tip where it spreads out and 

 flows back peripherally in the manner of a fountain flow. The 

 granules heap up around the base of the bulge where, by means of 

 a jellying process, a semisolid wall is built about a central liquid 

 channel. Retraction of a pseudopod is accompanied by a reversal 

 of the jellied to a liquid state. 



An undisturbed Amceba usually forms numerous pseudopodia. 

 Upon continued agitation a broadly lobate pseudopod is formed. 

 The jellying process of the backward flowing endosarc is di- 

 minished. The base of the pseudopod, consequently, broadens 

 more and more until all of the endosarc reverts to a liquid state 

 and the entire body of the Amceba becomes transformed into what 

 one may term a single pseudopodium within which vortical 

 currents occur analogous to those of a chloroform drop creeping 

 along a bed of shellac under water. 



The motile activities of an Amceba depend upon a delicate 

 balance between the liquefying and solidifying tendencies of its 

 protoplasm. The most recently solidified regions are the ones 

 that most readily liquefy. In this way a gradient exists with a 

 definite antero-posterior axis. The posterior end consists of a 

 heaped up mass of jellied material which is more resistant than 

 other parts to the liquefying process necessary for the formation 

 of pseudopodia. In an actively moving Amceba the amount of 



