646 Lewis. — The Life History of Grijfithsia Bornetiana . 
not discuss the question of simultaneity of nuclear division, but leaves the 
reader to infer that the mitoses in a cell do not occur at the same time. 
The same is true of Berthold’s work on Codium (6), and of Fairchild’s 
account of Valonia ( 27 ). 
Approximate simultaneity of nuclear division may be said to be a very 
general phenomenon in multinucleate plant cells. 
The small size of the nuclei renders Grijjithsia a rather unfavourable 
object for the study of the details of mitosis. The following account is 
based on observation of the nuclei in vegetative cells of the tetrasporic 
plants. 
The nuclei are throughout their history very poor in linin. The 
chromatin of the resting nucleus is not, therefore, distributed on a linin 
reticulum, but is contained in a centrally placed, homogeneous nucleolus, or 
karyosome (Fig. 10). It seems possible that a small amount of chromatin 
is distributed on the peripheral linin network, but the bulk of it is certainly 
in the nucleolus. As the nucleus prepares for mitosis, it increases somewhat 
in size, becoming about 4-5 /x in diameter ; the nucleolus also enlarges. 
Chromatin from the nucleolus, in the form of rather large granules, passes 
out to the periphery of the nucleus along faint linin strands (Figs. 14, 1 5), 
very much as was described by Wolfe in Nemalion ( 90 ). At the same time, 
the nucleolus becomes differentiated into faintly and darkly staining areas, 
the latter probably representing chromatin. The chromatin continues to 
pass out of the nucleolus until the whole chromatin content is distributed 
through the nuclear cavity in the form of granules, some of which are con- 
nected with one another by linin threads (Figs. 11, 12, 13, 14, 15, 16). The 
number of these granules seems in every case examined to be more than 
twice the number of chromosomes, and in some instances the granules 
become much more numerous. The granules now approach the centre of 
the nucleus, at the same time becoming fewer in number, probably by the 
fusion of separate granules (Fig. 17). As they move toward the centre, 
they become arranged roughly in a flat plate, though all the granules do not 
lie in exactly one plane (Fig. 18). While this is going on, a faint spindle 
is formed, apparently by the rearrangement of the linin threads (Figs. 18, 
19). The spindle fibres are connected with small, darkly staining kino- 
plasmic caps, which lie on the nuclear membrane at opposite poles of the 
nucleus (Fig. 19). 
At metaphase the spindle is seen to be short and broad and more or 
less truncated at the ends (Fig. 21). The nucleus is flattened at right 
angles to the axis of the spindle, so that it is broader than long. The 
chromosomes are closely packed on the equatorial plate, which is nearly 
as broad as the nuclear cavity. The nuclear membrane is intact, so that 
the whole spindle is intranuclear. 
In addition to being closely packed, the chromosomes do not lie in 
