408 Collins .— The Structure of the Integumentary System of the 
(c) That with longer periods of immersion infiltration of the solute 
probably occurred through the tissues of the furrow, and that this infiltration 
took place more rapidly at the germ end. 
Section V. The Spread of Enzymes on Germination and 
the Path of Liquid Penetration. 
Brown and Morris ( 2 ) showed that the germination of the barley grain 
embryo was accompanied by a definite progression of the disintegration of 
the endosperm by the action of enzymes. It was stated that the mass 
of residual cell-walls lying in con¬ 
tact with the scutellum, particu¬ 
larly its upper two-thirds, was 
the first to be dissolved, whilst 
the one-third part adjacent to 
the furrow side of the grain 
still to some extent retained its 
structure. Progress of disinte¬ 
gration proceeded from proximal 
to distal end, but more rapidly 
immediately under the aleurone 
layer. The cells and their con¬ 
tents lying below the corrosion 
area were then gradually dis¬ 
solved by the deeper penetration 
of the enzymes (see Fig. 9). At 
this time it was sought to prove 
that the enzymes active in dis¬ 
integration were wholly produced 
by*» the epithelial cells of the 
sctitellum. 
Brown and Morris concluded 
that the early disintegration of 
the peripheral starch cells was because these cells were younger and their walls 
less resistant to enzyme action. This explanation cannot be regarded as satis¬ 
factory, inasmuch as it is generally understood that the parietal cells of the 
endosperm are the first to be laid down and provided with walls. An 
examination of the developing grain of barley showed that this was no 
exception to the general rule; indeed, the aleurone cells forming the 
parietal layers possess very thick and highly resistant walls, although they 
are not cuticularized, as is usually stated. 
Haberlandt’s ( 10 ) account of the progression of enzyme action is, in the 
writer’s opinion, more detailed and exact. He stated that corrosion of the 
starch granules first occurred between the scutellum and the aleurone layer 
Fig. 9. Progress of starch disintegration by enzyme 
action. Enzyme action first occurs in cross-hatched 
area, then in doited area, and subsequently as indicated 
by broken lines. 
