ROLE OF NUCLEUS IN CELL FUNCTIONS. 387 



water into the protoplasm. Later the property of imbibition is 

 reacquired. If the contractile vacuole is in the enucleated frag- 

 ment at the time of enucleation, it disappears completely when 

 the fragment becomes wrinkled (Figs. 5 and 6) and does not 

 again appear until streaming is resumed (Fig. 7). Fourth, 

 enucleated fragments, often show a tendency to move in a Umax 

 or monopodal fashion. Fifth, the removal of the nucleus does 

 not affect noticeably the ability of the amoeba to adhere to the 

 substratum and thus approximate normal locomotion. Sixth, 

 the solation-gelation (Mast 1923) process continues in enucleated 

 amoebae. 



It should be noted, however, that in many cases where to 

 casual observation it appears that an enucleated fragment is 

 moving normally, a closer scrutiny and comparison with a normal 

 amoeba shows that the movement is not quite natural. It is 

 difficult to get any quantitative data regarding the degree of 

 normalcy of amoeboid organisms. The tendency to move in a 

 Umax fashion, which A. dubia rarely does normally, is the most 

 perceptible deviation from the normal. 



There are other irregularities which one finds, such as the 

 tendency of the enucleated Umax form to flow in one direction 

 for a while, and then very suddenly contract at the anterior end 

 and flow in the opposite direction. Occasionally an amoeba will 

 flow in opposite directions from the middle for a short time, in 

 which case the neck of protoplasm connecting the two streaming 

 units becomes very thin. These phenomena seldom occur in 

 normal nucleated specimens. 



Stole has made the assertion, and laid much stress upon it, 

 that enucleated amoebae show the same irritability as nucleated 

 ones. That is to say, they show what he has designated as the 

 equilibrium condition when streaming unmolested (Fig. I.), and 

 the stimulated condition when stimulated mechanically (Fig. n). 

 In experiments like the one described above, the amcebae were not 

 disturbed for a while after cutting. A number of experiments 

 were performed in which the amoebae were disturbed just after 

 cutting and at other times. The following is a typical experi- 

 ment. 



At 3:12 an amoeba was cut into two approximately equal 



