41 o Collins . The Structure of the Integumentary System of the 
centimetres of water contained in watch-glasses. Some thin starch solution 
was made by boiling a little potato starch in water and diluting it; 20 c.c. 
were put into each of three small flasks. To A the furrow portions, together 
with the steeping liquid, were added; to B the portions from the curved 
surfaces ; to C nothing at all. All were maintained at 50° C. 
After eight hours 2 c.c. were withdrawn from each flask, and succes¬ 
sively tested for sugar by adding three drops of Fehling s solution and 
boiling. A gave a copious precipitate, as it did even after four hours ; B 
became foggy, and C remained unchanged. After twenty-four hours, A gave 
an abundant precipitate ; B, a very evident one; C, none. Finally, iodine 
was added to the remaining fluid in each flask; that in A and B gave no 
starch reaction ; that in C did. Whilst, however, the boiled starch solution 
had been completely converted, the starchy tissue attached to the portions 
of material in B reacted with iodine. During the experiment the furrow 
portions had swollen greatly and become soft, while the chips from the 
curved surface of the grain had swollen but little. The early conversion of 
the starch to sugar in the first flask might be related to a capacity of the 
furrow tissue to swell more quickly, and the contents of its cells to diffuse 
more readily. Considerable quantities of enzyme must, however, be present 
in the cells of the furrow tissue at its germinal end. 
It will clearly be evident from this section that the spread of enzyme 
action is readily explicable on the theory of the uptake and distribution of 
penetrant liquids put forward in this paper. Hitherto it has been assumed 
that, when grains are steeped in water, uniform absorption occurs over the 
whole surface of the grain, and the effect of a special localized entry with 
a rapid distribution in the sub-aleuronic starch layer of the curved surface 
has not been considered. In the opinion of the writer, failure to recognize 
the local uptake of water and its subsequent peripheral distribution has led 
in a large measure to the conflicting results which have been obtained by 
investigators of the problems previously mentioned. Even when embryos 
or other parts have been excised from the dry resting grain preparatory to 
experimental work, it is quite possible that a casual wetting during 
harvesting, or after, may have served to distribute enzymes within the 
endosperm. 
Section VI. Discussion of the Possible Paths of Easy 
Penetration in the Germinal Region of the Grain. 
It is now clear that somewhere in the germinal region of the grain 
there is a path of easy permeability. As it has not been found possible to 
locate the precise path by direct experimental work, for the adequate 
reasons previously given, it becomes necessary, in discussing the possible 
point of entry and seat of selective action, to take into consideration the 
