32 
under the action of hot water or mineral acids was a purely 
secondary phenomenon, and dependent on a condition in- 
duced in the granule by the action of these reagents. The 
immediate effect of this action is a swelling up of the granule, 
but the latter, not at once responding to the action of the re- 
agents uniformly over its whole surface, certain portions of the 
surface are first elevated into ridges or projections, which neces- 
sarily leave depressions of greater or less depth between them, 
and the appearances which have been mistaken for an unrolling 
or unfolding of the original granule are due to the act of 
formation of these ridges, but especially to the rolling outwards 
of the intervening depressions when these, in their turn, al- 
most immediately afterwards, respond to the action of the re- 
agents. 
The author believes that there is no difficulty in demon- 
strating in the most undeniable way the composition of the 
starch granule out of a series of hollow concentric lamelle. 
If potato starch previously exposed to the prolonged action of 
a rather weak alcoholic solution of iodine be treated under 
the microscope with sulphuric acid diluted with about one- 
fourth water, the granules will, for the most part, present a 
beautiful dissection of the lamelle from one another, which 
will then be plainly seen to consist of a series of hollow con- 
centric shells. In this experiment a solution was generally 
employed formed by mixing equal parts of water and the com- 
mon tincture of iodine; and the granules were exposed to its 
action for the space of two or three weeks. 
The author also maintained, that while the various la- 
mellz are probably all identical in chemical composition—for 
they present no difference in their behaviour towards iodine,— 
they possess, nevertheless decided differences of another kind, 
which appear to be referable to conditions of integration. 
These differences are beautifully demonstrated by the ac- 
tion of acetic acid on the granule, previously slightly iodinized 
and treated with sulphuric acid ; when thus operated on, the 
