46 WARREN H. LEWIS 
to this degenerative fragmentation of the nuclei, more normal 
binucleate cells are not uncommon in cultures of all ages. 
Binucleate cells. Macklin (16) found that binucleate cells 
were more numerous in cultures from the hearts of chick embryos 
of five days’ than in those of eight days’ incubation and that 
they were more numerous in the two-day- than in the one-day- 
old cultures. He found, furthermore, that the average binu- 
cleate cell was approximately twice as large as the mononucleate, 
and that each nucleus was very similar in size, shape, and general 
appearance to the nuclei of the mononucleate cell—findings which 
my own observations have confirmed. I have further noted 
that there is a very decided increase in the mitochondrial con- 
tent. Figure 10 shows a very large binucleate cell—a giant 
compared to its neighbors. Each nucleus seems to be as large 
as normal, while the cytoplasm is more than twice that of the 
largest mononuclear. ‘The mitochondria are of the same general 
character (granules and rods) as those in the neighboring cells, 
but are almost, if not fully, fourfold in number. 
Nucleolus. The nucleoli vary in number from one to four 
and also vary in position, size, and form. In some of the older 
cultures the nucleoli are extruded from the nucleus, usually 
from one end (fig. 24). The exact details of this process have 
not as yet been carefully followed. The nucleolus in some way 
reaches the end of the nucleus and les against its membrane. 
Disintegration then takes place in this region, the nuclear mem- 
brane disappears, a vacuole-like area develops in the adjoining 
cytoplasm, and the nucleolus eventually comes to le within it. 
Cytoplasm. In the living cultures both ectoplasm and endo- 
plasm appeared homogeneous. In the fixed material the ecto- 
plasm was sometimes homogeneous and sometimes striated 
(figs. 16 and 17). ‘These striae were not seen in the living cells, 
but formed as the cytoplasm coagulated under the influence of 
the iodine vapors. Ido not believe they correspond to preformed 
structures. They varied in size and ran out into processes 
often to their very tips. This would seem to indicate that the 
peculiarity of the ectoplasm which causes it to coagulate into 
fibrillae is a molecular thing associated with tension, due to the 
