345 
the Embryo-sac Mother-cell of Li Hum. 
Fig. 1), the nucleus contains one to three large nucleoli and sometimes 
several additional smaller ones. The linin is disposed in a very delicate 
network, with many delicate threads extending radially from the larger 
nucleoli. The chromatin is distributed upon the linin threads in small 
granules. Here and there are to be seen larger aggregations of chromatin 
granules at the angles of the linin meshes (Fig. i). This is the structure of 
the typical resting nucleus. 
Each figure of the nucleus is accompanied by an outline drawing of 
the ovule in which the nucleus is found. Certain stages in the develop- 
ment of the ovule correspond rather closely with certain steps in the 
prophase of mitosis, so that the form of the ovule is helpful in enabling 
one to determine the correct stage in karyokinesis, especially when there 
is some variation in the form of the chromatin, due to the reagents or 
other causes. As will be seen from Fig. i a , the ovule from which Fig. i 
was taken was not only exposed to the direct contact of the fixing fluid, but 
a little of the ovule itself (only the epidermis in this case) was cut away 
along the line x-x. In this and in neighbouring ovules in the same sec- 
tion, the beginning of the outer integument was just perceptible as a 
slight bulging out of a few epidermal cells. 
In Fig. 2 is shown a nucleus which, judging from the stage of 
development of the ovule to which it belonged, and from the size and 
form of the cell, seems to represent the same stage in mitosis as Fig. i. 
One very large and two or three small nucleoli are present. The chro- 
matin, however, presents a striking contrast from that of Fig. 1 or of a 
later stage. Here we have rather large angular lumps of chromatin and 
a sparse linin reticulum, a condition which, it seems to the writer, may be 
due to the action of the fixing fluid. In this case the wall of the ovary 
was only partly cut away, so that the fixing fluid must first pass through 
a layer of tissue of six or seven cells in thickness before reaching the 
ovule. In nearly all preparations of this kind, the nucleus reveals a similar 
disposition of the chromatin, and the writer is of the opinion that the 
lumpy nature of the chromatin in this nucleus is due partly, if not wholly, 
to the action of the fixing fluid. Fig. 2 a is an outline of the section 
of the ovule containing Fig. 2. Owing to the shape of the ovarian cavities, 
it sometimes happens that the nucellus of the developing ovules is pressed 
against the inner wall of the loculus, especially in the ends of the ovary, 
thereby becoming somewhat truncated as in Fig. 2 a. In other parts of the 
loculus the nucellus has more room to elongate and round out at this stage 
in the development (Fig. 3#). With further growth the nucleus increases 
in size, and the chromatin granules (not the lumps of Fig. 2) not only 
become larger, but they are more regularly distributed upon the linin frame- 
work, whose meshes are now larger (Fig. 3). The change in the nuclear net 
from that of Fig. 1 to Fig. 3 foreshadows the transformation into a con- 
B b 2 
