REMC EY Ce SEU EEE NR eh ts, CAen rs Pee ly IS air = 
EA Soak ese So ics ea See Re A eee Meters 
; : : ee a - oh : Cees 
1910] CHAMBERLAIN—DIOON EDULE 425 
but not full of liquid. The cells disorganized in the formation of 
the cavity must have contributed largely to the growth of the 
suspensor, since the embryo itself is receiving from surrounding 
cells enough to account for any increase in its size. That the 
suspensor exerts a vigorous thrust is evident from the fact that 
when released it relaxes like a spring which has been under tension. 
The suspensor when stretched out reaches a length of 75 mm. As 
the embryo matures, the suspensor does not disorganize, but 
remains as a tough dry thread, strong enough to lift the weight of 
the entire embryo. . 
The embryo develops rapidly, cell division taking place through- 
_ out the entire embryo, while the suspensor cells elongate and also 
occasionally undergo mitosis (figs. 10-12). In the last figure 
the two upper mitoses are in the suspensor and the three lower 
in the embryo proper. It is interesting to note that such mitoses 
are found in cones which have been taken from the plant in southern 
Mexico, shipped to Chicago in a basket, and after arriving have 
been lying on the laboratory table for two or three weeks. 
The first indication of any differentiation of the embryo proper 
is the appearance of increased vigor in cell division in the region 
just below the suspensor, indicated by x in fig. 14. This region, 
which appears in the embryo and not in the suspensor, is the 
beginning of the coleorhiza, an organ which rapidly becomes . 
conspicuous and soon constitutes the largest part of the embryo 
(figs. 15, 16). 
While the coleorhiza and the root cap are spoken of as two 
organs, and while they differ widely in general appearance, in 
cell structure and in function they are morphologically only one 
organ, the root cap. The coleorhiza at first consists of thin-walled 
cells with numerous large starch grains, but toward the close of 
the intraseminal period the cell walls become very hard and thick, 
so that the term coleorhiza is quite appropriate. Just within the 
coleorhiza the mature embryo shows a cone of thin-walled cells, 
tich in tannin, derived from the same meristem, the beginning of 
which is seen in fig. 14. These cells are the outer layers of the 
Toot cap. At germination the pressure is developed, at least in 
large part, by the activity of the meristem which is adding new 
