437 
Embryo of Cryptomeria Japonic a. 
nuclei of the middle and upper tier, but not between the free nuclei of the 
upper tier. The result of this division is shown in Fig. 57. We have now 
in the pro-embryo two tiers of cells and one tier of free nuclei. The cyto- 
plasm of the cells is very densely granular, containing an abundance of 
starch. It stains very deeply, and presents a very sharp contrast to the 
clear cytoplasm of the archegonium above, in which the tier of free nuclei 
lie embedded. 
Arnoldi’s (’ 01 ) account of the development of the pro-embryo in 
Cryptomeria is rather meagre, but the four stages which he figures agree 
with my own observations. With the exception of the first two divisions, 
Coker’s (’ 03 ) account of the pro-embryo of Taxodium agrees very closely 
with that here given for Cryptomeria. 
The next stage in the development of the embryo is the elongation 
of the middle tier of cells. The development of the suspensors from these 
cells was followed very closely ; many preparations showing all the essential 
stages in this formation. Fig. 58 shows that cells of the middle tier have 
become much longer than the original archegonium, and as they grow, 
they carry the lower tier of cells downward through the tissue of the 
prothallium. At first the suspensors elongate in a straight line, but, as 
shown in Fig. 58, they soon become more or less curved. As they increase 
in length, this curvature becomes more marked, until they assume a distinct 
winding form. This curvature and winding in and out of the suspensors 
may be explained on the assumption that the rate of growth of the cells is 
very much greater than the rate with which they can be forced through the 
solid cellular tissue of the prothallium. As they wind in and out in all 
directions, it is impossible to observe their exact length or direction of 
growth in a single section. Fig. 59 represents a longitudinal section of the 
older suspensors with an embryo at the tip. It will be seen that a portion 
of the suspensors has been cut away in sectioning on account of the 
direction of their growth. It will also be observed that the suspensors are 
enormously long, and if they were stretched out their full length they 
would reach over half the length of the prothallium. 
In the stages older than that shown in Fig. 59, it was impossible to 
trace back the suspensors to their point of origin. With so many suspensors 
from the various archegonia, all growing together and winding in and out 
in all directions, the upper region of the prothallium showed nothing but 
a confused tangle of long suspensor cells. 
It was very difficult to estimate accurately the number of embryos 
developed from one archegonium ; my preparations showed a marked 
variation in this respect. The suspensors from several archegonia were 
sometimes found growing downward close together, and in such cases it 
was impossible to say definitely whether a series of suspensors came from 
one or more archegonia. By the time the suspensors reached the stage 
H h % 
