154 VICTOR E. EMMEL 



c. Derivation of plastids fro7n erythroblasts hy a process oj 

 cytoplasmic constriction 



Circumstances necessitated beginning the culture in the after- 

 noon. Having been made, they were then placed in the incubator 

 and observed as frequently as possible, the more favorable prepa- 

 rations being kept under observation for several hours or even the 

 entire day. During the earlier part of the investigation, atten- 

 tion was especially directed to those erythroblasts which seemed 

 to be most advanced in differentiation as indicated by the in- 

 creased amount of hemoglobin and the smaller, more compact, 

 pyknotic and eccentrically located nuclei. These cells were care- 

 fully observed for continuous periods of time, to ascertain, if 

 possible, steps in the process of their transformation into non- 

 nucleated erythrocytes, and whether the evidence would indicate 

 this process to be in the nature of an extrusion of the nucleus from 

 the erythroblast, or its disintegration and dissolution within the 

 cell body. Biased by the prevalent view that the nucleus even- 

 tually disappears from the erythroblast either by an intracellular 

 disintegration or by extrusion, it was with considerable surprise 

 that no conclusive evidence was obtained for either of these alter- 



potentiality for amoeboid movement, admitted to be present in the undifferen- 

 tiated progenitor of the red blood cell, disappears in the course of subsequent cyto- 

 morphosis, or whether in certain cases the phenomena may manifest itself in a 

 degree even in the more mature erythrocyte as described by Morris and Thayer 

 ('11), who observed activities in large erythroblasts or megaloblasts in cases of 

 anemia which, after due consideration of hemoglobin content, crenation, osmosis, 

 they interpreted as amoeboid in nature. They also describe the observation of 

 "exactly the same changes in shape in macrocytes (figs. 4-6, 35-37, 39-45, 98-102, 

 108-112, 113-118, 119-125). The rapidity of change may be quite as great as in the 

 nucleated red corpuscles and may present all the varieties observed in the latter. 

 There was no discoverable difference in kind or in degree. As in the case of the 

 megaloblasts, not all of the macrocytes exhibit amoeboid movements (fig. 11). 

 That non-nucleated cells should do so at all seems strange. But if the motility 

 of the megaloblasts is in reality amoeboid — and to the writers there appears to be 

 no other explanation — then there can be no doubt that certain macrocytes, too, 

 are possessed of it" (p. 6). Cytoplasmic movements apparently amoeboid in 

 character have also been noted by Schultze ('64, p. 358) in the red blood cells of ^ 

 young chick embryos, by Dekhuyzen ('92) in the nucleated erythrocytes of am- 

 phibian larvae, and by Ruzicka ('03, p. 306) in the red blood cells of the frog. 



