466 
EDWARD F. WOODCOCK 
(15) has found in the animal kingdom that the nucleus of the pan- 
creatic cell does not play an active role, but indirectly controls the 
zymogenesis. Haidenhain and Korshelt consider that the changes 
in position and size of the nuclei during secretion are signs of functional 
nuclear metabolism. 
There is associated with the increase in size and granularity of the 
aleurone cells in Rumex sl gradual change in the endosperm and 
embryo. This change is seen in the endosperm as a slight depletion 
of the starch cells next to the thickened micropylar portion of the 
aleurone layer and next to the embryo. Perhaps the depletion in 
the latter region is entirely due to a ferment secreted by the embryo 
itself. Newcombe (16, p. 71) has found in the buckwheat that the 
cotyledons do actually secrete a ferment which has a weak solvent 
power on wheat-starch grains, and on the membranes of the barley 
endosperm. This may be true for Rumex but it seems more probable 
that the aleurone cells, which at this time have every appearance of 
active digestive cells, are secreting an enzyme which is the principal 
agent in' the dissolution of the starch in the endosperm. This enzyme 
diffuses to the starchy endosperm in the watery solution about the 
embryo. As a result of the action of the enzyme on the starch, there 
is a conversion of the insoluble starch into a soluble form, in which 
form it is absorbed by the embryo. In connection with the transfer 
of the dissolved starch to the germinating embryo an interesting 
phenomenon may be noted. As the carbohydrate solution is absorbed 
by the growing embryo, instead of being entirely consumed at once 
by the growing embryo, as is assumed to be the case in endosperm- 
containing seeds, a part of this absorbed solution is converted back 
into the insoluble form and stored in the cells of the embryo in the 
form of compound starch grains. The depletion of the starch cells 
continues, consecutively towards the outside of the seed, the depleted 
endosperm cells in contact with the embryo becoming collapsed by 
the pressure of the latter. As the micropylar portion of the aleurone 
layer becomes exhausted through continued secretion, the basal thinner 
portion comes into activity, each individual cell acting independently 
of those adjacent. 
If attention is now turned to a consideration of the changes in the 
embryo associated with the activity of the aleurone layer and the 
dissolution of the starch, it is seen that important changes are taking 
place. There occurs a rapid elongation of the embryo. This elonga- 
