GAGER: GLANDS IN THE EMBRYO OF ZEA 129 
The work of Griiss indicated that the statement of Brown and 
Morris (1890), “that the disappearance of the cell-wall always 
precedes any visible attack upon the contained starch granules,” 
is not true in all cases. 
It would lead too far afield to review in detail the subsequent 
literature upon this topic. Experimental researches have led to 
at least five different views as to the place of origin of the digestive 
ferment during the germination of grasses. They may be briefly 
summarized as follows: 
1. Lhe cells of the aleurone layer chiefly secrete the diastase, 
which acts on the starch in the endosperm. This is the statement, 
in a more modern terminology, of the old view that starch is 
turned to sugar by gluten. It was tacitly assumed by Tschirch,” 
in 1889 (page 181, legend of 63).* 
2. The epithelium of the scutellum is the principal secreting layer. 
This is the view of Brown and Morris,”* in 1890,+ of Griiss,” in 
1893 (page 291), and, by implication, of Reed,” in 1904. <Ac- 
cording to Brown and Morris, a diastase that dissolves cell-walls 
is also secreted by these cells. 
3. The endosperm is the main source of the ferment, according 
to Green ?! (1890), Krabbe ® (1890), and Linz* (1896). ‘“ The 
diastase,” says Krabbe, ‘‘is generally not translocated, but de- 
velops directly at the place of its activity.’’ Secretion by the 
endosperm results “in consequence of some kind of stimulus 
on the part of the seedling.”” This last assertion was contra- 
dicted by Pfeffer ® in 1893. Linz* definitely states (page 301), 
“that the epithelium of the scutellum of the seed of maize is not 
a condition to secrete ferment, [and] that the epithelium is rather 
an apparatus which serves for the absorption of dissolved nutri- 
ment.” Further on (page 318) he says, “The aleurone layer is 
not the source of the diastase which appears in the endosperm 
during germination.” 
ot The scutellum and the endosperm secrete diastase, but not so 
*The notion that pure gluten can change starch to sugar is now, of course, 
: y erroneous, but whether or not the cells of the gluten- or aleurone-layer 
o the grass-fruit can secrete a diastatic ferment is a different question. 
Tt Brown and Escombe !§ (page 14) demonstrate the hydrolytic capacity of aleurone- 
cee barley, capacity of this layer for endosp depletion, and that such capacity 
_ on the part of the endosperm-cells is very probable. 
= 
