348 
Proceedings of Royal Society of Edinburgh. [sess. 
Method of Examination. 
The intestines of the animals were examined, in the earlier 
experiments, in three different ways — by scraping, by cutting 
sections with the freezing microtome, and by sections cut in 
paraffin. In the first case, the intestine, at varying distances 
below the entrance of the pancreatic duct, was opened as soon as 
the animal had been killed by chloroform ; the villi were scraped ; 
the scrapings were spread out on cover-glasses, mounted in 2 per 
cent, osmic acid, left for several hours, and then examined in the 
same fluid, or in glycerine run in beneath the cover-glass. 
In the second case, the portions of intestine taken were put into 
a large quantity of 2 per cent, osmic acid for twenty-four hours, to 
ensure a thorough blackening of all fat, and were then cut at once 
with the freezing microtome, and examined in glycerine. 
In the third case, after fixing as above in osmic acid, the pieces 
of intestine were washed in water for twenty-four hours, then 
rapidly hardened in alcohol of increasing strength, cleared on xylol, 
left in the paraffin bath for twenty-four hours, cut in the usual way, 
and mounted in xylol balsam. Flemming has shown that xylol, of 
all the clearing agents, has least effect on fat which has been 
blackened by osmic acid. We took care to expose the specimens to 
absolute alcohol and xylol for the shortest time that was consistent 
with complete dehydration and clearing, and we found, after the first 
half-dozen experiments, that our specimens, prepared in this way, not 
only showed no signs of solution of fat having taken place, but that, 
from the more perfect clearing of the tissue, we could see fat in them 
in cases where it was not to be made out by the two first methods. 
The paraffin sections had also, of course, the advantage of being 
much clearer and more regular in thickness than those cut by freezing. 
In the later experiments, therefore, we confined ourselves 
entirely to the last method. We were careful, in almost every 
case, to examine at least two pieces of intestine, one taken a few 
inches below the pancreatic duct, the other at a lower level, near 
the termination of the small intestine. 
Experiments. 
Experiment 1 Oats deprived of Fats.~\\0 grins, of oats were 
