ROLE OF NUCLEUS IN CELL FUNCTIONS. 385 



respectively (Stole, 1910). It is possible that some of the 

 variations in length of life are due to the species of amoebae 

 employed by the various workers. 



In order to ascertain the effect of the removal of the nucleus 

 upon the locomotion of the amoebae, sixty-four experiments were 

 performed, and carefully recorded. Each amoeba was under 

 observation for a few hours after cutting, and was studied at 

 frequent intervals afterwards so long as it showed any activity. 

 The following experiment is typical of the greater number of the 

 experiments and will be given somewhat in detail. 



An amoeba moving actively in a healthy culture (Fig. i) in a 

 Syracuse watch glass was bisected at 3 144 so as to stimulate it as 

 little as possible. The protoplasmic streaming was not discon- 

 tinued in either piece (Figs. 2 and 3). The fragments moved 

 away, however, in opposite directions from the plane of cleavage, 

 as invariably happens when a clean cut is made so as not to 

 agitate the amoeba too much. At 3:45 both portions were still 

 moving, attached to the substratum, as determined by directing 

 a fine stream of water from a pipette upon them. At 3:49 both 

 were still progressing normally. But from 3:49 to 3:54 the 

 activity of the enucleated part slowly diminished (Fig. 4), it 

 lost its hold on the substratum, and the extended pseudopods 

 appeared literally to shrink into short, stubby, wart-like processes 

 (Fig. 5). Under the higher power of the microscope it was 

 apparent that the surface of the fragment was wrinkled and that 

 the clear zone of ectoplasm around the periphery had disappeared, 

 the granular protoplasm extending throughout. Meanwhile the 

 nucleated portion continued to move quite naturally. Later it 

 was placed in a moist chamber where it ingested food and divided 

 two days later. From 3 :54 to 5 123 the enucleated fragment re- 

 mained in the irregularly spherical shape, with the surface con- 

 siderably wrinkled (Fig. 6). The shape changed somewhat from 

 time to time, but almost imperceptibly. At 5:23 it sent out a 

 long pseudopod (Fig. 7) and commenced a slow streaming, but 

 because it was not attached to the substratum there was no 

 progressive movement. At six o'clock it was attached and 

 streaming actively in an irregular Umax fashion (Fig. 8). During 

 the next two days it was attached and streaming actively in a 



