282 Reed. — A Study of the Enzyme-secreting Celts in the 
granules already present rather than to an increase in their number. The 
nucleoli show a slight increase in size. 
The morphology of cells in embryos fourteen days old (Fig. 10). With 
the exception of a few layers of marginal cells, the granular contents of the 
absorbing organ have disappeared, and from this time forward there is no 
indication of metabolic activity in any except the surface-layers of cells. 
The epidermal cells are not only increasing in size, but numerous examples 
of karyokinetic division indicate that they are increasing in number. The 
staining reactions indicate that they are not so cyanophil as in the stage 
last described. The cytoplasm is beginning to show a diminution in the 
amount of granular material present. The finer granules seem to be the 
first to disappear. After their number has been diminished, it can be seen 
that the granules lie on the cytoplasmic network, not in its meshes. 
The nuclear chromatin does not increase as fast with increased activity 
as in the case of Zea, yet there is an increase. The nucleolus, instead of 
diminishing, has up to this time retained its original size, and shows a strong 
affinity for stain. 
The morphology of cells in seedlings eighteen days old (Fig. 11). The 
cells are much the same, except for continued elongation, as in the pre- 
ceding stage. Their staining qualities indicate that they are becoming 
more erythrophil. 
The morphology of cells in seedlings twenty -six days old (Fig. 12). At 
this stage the cells of the absorbing organ are practically free from granular 
material. There are a few erythrophil granules in the marginal cells. The 
deeper-lying cells which originally contained proteid material have enlarged 
to several times their former size, and the protoplasm remaining forms 
a thin parietal layer. The elements of a vascular system have begun to 
make their appearance among the marginal cells of the absorbing organ. 
There are three morphological differences between the nuclei of this 
and preceding stages — (1) they are smaller in volume; (2) the nucleoli are 
also smaller and often surrounded by a vacuole ; (3) there is an increased 
amount of chromatin in the nucleus, which occurs in the form of small grains 
on the linin network at the surface of the nucleus. 
The morphology of cells in seedlings thirty-three days old. At this 
age the absorbing organs are white elliptical disks about 8 or 10 mm. 
diameter and 3 mm. thick. The epidermal cells have lost much of the 
cytoplasm which they previously contained, many of them containing only 
a parietal layer. The most noticeable change is in the number of granules 
present in the cytoplasm (Fig. 13). It may be that part of the protoplasm 
has broken down to form an enzyme. The nuclei are not much smaller, but 
the nucleoli are diminished in size. The amount of chromatin is less also. 
The morphology of cells in seedlings four months old. The seedlings 
from which the material for this study were obtained were grown in earth 
