14 BOTANICAL GAZETTE [JANUARY 
of its cells is the first step. Fig. 38 shows an early stage in 
this growth. As soon as it begins the cap cells begin to dis- 
integrate and are soon crushed (figs. 38 and 39). At first all the 
cells divide with equal rapidity. Very soon the upper cells show 
a tendency to enlarge, and more especially to elongate, while the 
lower ones continue division unabated. An early stage of this phase 
of development is shown in fig. 39 and a later one in fig. 40. The 
proembryo now consists of two regions: (1) The very actively 
dividing cells at the tip constitute a large apical meristem, and 
(2) the cells behind the meristem gradually cease division and 
elongate so as to produce a massive secondary suspensor which 
pushes the proembryo still farther down into the endosperm. 
After a time (a month or so) the proembryo consists of a massive 
suspensor and a large cylindrical body of meristematic tissue. 
The activity of the apical meristem practically ceases. 
Embryo 
Three new meristems are now developed. The first of these 
is picked out where the suspensor joins the main body and is to 
form the growing point of the hypocotyl. The other two form 
either side of the original growing point and quickly develop the 
two cotyledons. The remains of the primary meristem constitute 
the meristem of the stem apex, which continues dormant until 
some time after germination of the seed. Fig. 42 shows a longi- 
tudinal section of such an embryo some time in early September. 
All the regions of the embryo are now in course of development. 
Stem and root apices, cotyledons, and vascular tissues are clearly 
in evidence. These regions continue growth for two months or 
more before the seeds have reached ‘the shedding stage. Growth 
in this period is largely confined to the cotyledons, which become 
very large in comparison with the hypocotyl. 
The distribution of the vascular tissues in the embryo is shown 
in figs. 42-44. The cotyledons are traversed by 7 vascular bundles. 
Each of these can be traced backward to its separate union with the 
vascular cylinder of the hypocotyl. In the latter the procambium 
strands form a hollow cylinder. Just below the origin of the 
