ACCOMPANYING THE SECRETION OF DIASTASE 425 
(7) If asmall quantity of cane sugar is added to the starch, the 
latter is protected ina remarkable manner. There is no sign of 
pitting of the starch grains as long as any sugar remains unab- 
sorbed by the embryo. ‘Thus the secretion of active diastase by 
the epithelium may be regarded to some extent as a starvation 
phenomenon.” 
(¢) Lastly, in addition to the starch-dissolving enzyme (amylohy- 
drolyst), there is present in the growing plantlet a cellulose-dis- 
solving enzyme (cytohydrolyst). Both these enzymes are 
secreted by the columnar ( ‘‘absorptive”’ ) epithelium. 
2. Observations.—In previous accounts of the secretion of 
diastase, the statement that the epithelial cells at the beginning of 
germination are filled with granules seems to be the nearest 
approach to an accurate description of its origin. This is true as 
far as it goes. I have attempted to trace these diastase granules 
to their ultimate origin and I think that there is evidence for the 
conclusion that in corn and barley and probably in all the Grami- 
neae, ‘‘ diastase of secretion”’ arises in the nucleus of the epider- 
mal cells of the scutellum. 
My earliest preparations of corn are sections of a kernel that 
had been soaked in water just long enough to soften the outer 
coats. The protoplasm of the columnar cells is found to be much 
shrunken owing to the dry condition of the resting seed. The nuclei 
for the most part stain very deeply, either wholly, or in several 
places, although here and there are nuclei which are clear. By the 
use of a high power this dark staining matter is seen to be distinctly 
granular (f 2). It stains fully as intensely as chromatin. These 
granules are often collected in little bunches. Sometimes a string 
of them lie about the vacuole of the nucleus. The granules 
Seem to arise along the course of the linin network, for many of 
them may be seen scattered throughout the reticulum. Even at 
this early stage the nucleus is often so packed with granules that 
it stains a uniform black and the granular constitution of the mass 
is shown only by its corrugated edge. In cases where the epi- 
dermal cell is double, ¢. ¢., where there is an inner and an outer 
cell, the nuclei of both produce these granules. 
Passing now to a kernel that has been placed a little longer 
_in conditions favorable to germination, we find the cytoplasm filled 
