3 86 Collins.—The Sir tic hire of the Integumentary System of the 
treated with swelling reagents, but mounted directly in alcohol or glycerine, 
and the next point determined was their behaviour towards various test 
reagents. 
A consideration of the class of substances able to penetrate the grain 
led one to think that possibly some lipoid material might be adsorbed by 
the walls of a particular layer, rendering it semi-permeable and able to 
function selectively. 
Reichard had found tannin to exist in a more or less continuous layer, 
and later pointed to the possibility of tannin acting when wetted as 
a colloidal semi-permeable membrane. In order to determine whether 
tannin was present, the writer soaked whole grains in ferric chloride, but 
sections cut from them, when examined, showed no reaction attributable to 
the presence of tannin. Sections were also steeped in ferric chloride, 
ammonia, copper sulphate, and afterwards examined, but tannin could not 
be traced. 
The results obtained with the more important reagents were as 
follows: 
Aik anna . Sections were placed in a freshly prepared solution of 
alkanna for twelve hours, washed, and mounted in glycerine. The cuticle 
of the paleae was stained red, as were three other membranes, namely: 
(a) the outermost surface of the pericarp, 
(b) the external surface of the tegmen, 
(c) the internal surface of the tegmen. 
The possibility that the layer (c) represents the outer wall of the 
epidermis of the nucelhis has been removed by the examination of the 
young ovule. The nature of the impregnating material reacting to alkanna 
was then determined. Fats, wax, suberin, cutin, resin, tannin, and ethereal 
oils react in this way. By a series of experiments the presence of resin, 
tannin, or ethereal oils was negatived. Some sections were dried carefully 
and immersed in chloroform or ether for a lengthy period. On sub¬ 
sequently treating these sections with alkanna or Scharlach R the mem¬ 
branes again reacted, staining red. Hence they were not impregnated with 
ordinary fatty material soluble in ether. The fat of the aleurone cells had 
been dissolved. 
A further endeavour was made to remove possible fatty material of the 
membranes enclosing the grain, by placing grains with ether in a Soxhlet 
tube and allowing extraction to proceed for some weeks. The grains did 
not lose the wrinkles in the skin and, judging from external appearance 
only, penetration of the ether into the grain did not occur. The ether was 
previously deprived of water. Sections taken from the grains and treated 
with alkanna or Scharlach R gave all the usual reactions, the fat globules 
of the embryo and aleurone cells, as well as the membranes mentioned 
above, being stained deep red. 
