386 ELERY R. BECKER. 



Umax fashion when observed (Fig. 9). On the third day the 

 streaming was slower, change of shape was not so rapid, the 

 attachment to the substratum was loosened, and the periphery 

 of the amoeba was a wide zone of clear ectoplasm (Fig. 10). On 

 the fourth day perceptible streaming and change of shape had 

 ceased, and the amoeba was called dead. 



From the series of experiments, certain definite facts were 

 learned. First, locomotion is not at once affected by the re- 

 moval of the nucleus if the amoeba is not agitated in the process 

 of cutting. Second, from five to ten minutes after enucleation 

 the amoeba commences to stream more slowly. This is ac- 

 companied by a gradual release of its hold on the substratum. 

 Third, the surface of the enucleated portion becomes wrinkled, 

 as if the pressure from within were reduced. Lynch too mentions 

 the fact that his amoebae assumed the shape of a corrugated 

 sphere about seven minutes after the removal of the nucleus- 

 Hofer's figures show that he too obtained it. It appears as if the 

 removal of the nucleus causes the cell to lose turgidity. Entire 

 amoebae placed in 20 per cent, sugar solution become wrinkled in 

 a similar manner after about fifteen minutes. Third, in about 

 two and one half to three hours after enucleation the streaming 

 is resumed, the amoeba attaches itself to the substratum, and 

 moves in a manner approximating normal streaming. More 

 often, however, it assumes a Umax shape, and moves after the 

 fashion of a monopodal amoeba, sometimes forming lateral 

 pseudopods, but only temporarily. Fig. 16 shows an enucleated 

 amoeba moving in an extremely normal fashion two days after 

 merotomy. Concerning the causes why the amoeba should again 

 become active after an interval of comparative inactivity, one 

 can only speculate. There must be a certain amount of pressure 

 within an amoeba before it can project a pseudopod. Mast says 

 that it is the contraction of the plasmagel and the hypertonicity 

 of the plasmasol which provides the mechanics of locomotion. 

 The pressure within is reduced when the nucleus is removed, but 

 is increased to some extent after an interval of two to three hours. 

 Certainly then the nucleus is not the centrum for controlling the 

 locomotion of the amoeba. Rather, due to some unknown 

 physical cause, its removal seems to affect the imbibition of 



