ACCOMPANYING THE SECRETION OF DIASTASE 423 
have been emptied by the pressure of the growing scutellum during 
the development of the seed, we find them most numerous where 
the scutellum is thickest. Directly adjoining the flattened empty 
cells is the epidermal layer of the scutellum, the cells of which 
manufacture the ‘“ diastase of secretion.” 
_ These secretory cells are found at every point where the scutel- 
lum is in contact with the endosperm. At the region of the tip 
this secretory epithelial layer dips down at frequent intervals into 
the scutellum. The convolutions so produced secure a larger sur- 
face of secretion where there is greatest need for the enzyme ; for 
the endosperm is thickest at this point and in front of the embryo. 
Immediately below the epithelial cells are the large loosely ar- 
ranged isodiametric cells of the scutellum. The larger cells are 
near the central part of the scutellum. Here, too, the cell walls 
are thicker than at the periphery. The young shoot itself, is 
closely connected with the lower central portion of the scutellum. 
From the hypocotyledonary part there proceeds into the scutel- 
lum a branch of the vascular system which soon divides into two 
Parts. One of these runs directly upward, and the other toward 
the tip of the scutellum. They both give rise to many small 
branchlets, but none of these find their way into the heel of the 
scutellum. 
The diastase-secreting cells are columnar, and at the beginning 
of germination are about three times as long as broad (f 2). 
The bases of the cells rest on the scutellar parenchyma, and their 
ends are in close apposition to the endosperm. The cell walls are 
extremely thin and delicate, thus permitting a free osmotic inter- 
change. The protoplasm in early stages is finely reticulated, but be- 
comes somewhat coarser as germination progresses. The nucleus 
varies greatly in its position. Although it is found as a rule near 
the center, it may not infrequently occur at the base or near the 
outer end of the cell. It is slightly elliptical with its long dimen- 
Sion parallel to that of the cell. The nuclear wall is very delicate. 
The chromatin, in the form of small granules, lies scattered in the 
linin network. The large, deeply staining nucleolus always lies 
in a vacuole. Two such nucleoli very commonly occur. Al- 
though as a rule round, a knot like projection is sometimes pres- 
€nt. The cells in the central part of the scutellum are especially 
