DIGESTION VISIBLE TO THE EYE. 
coat became sometimes red and dry, and at other times pale and 
moist , and lost altogether its smooth and healthy appearance. As 
a necessary consequence, the usual secretions became vitiated, 
impaired, or entirely suppressed; and the follicles from which, in 
health, the mucus that protects the tender surface of the villous 
coat is poured out, became flat and flaccid, and no longer yielded 
their usual bland secretion. The nervous and vascular papillae, 
thus deprived of their defensive shield, were then subjected to 
undue irritation. When these diseased appearances were con- 
siderable, the system sympathized, and dryness of the mouth, 
thirst, quickened pulse, and other symptoms shewed themselves; 
and no gastric juice could be procured or extracted even on the 
application of the usual stimulus of food. 
“ To enable ourselves to appreciate correctly the nature of 
digestion, we must begin by considering the conditions essential 
for its performance, or without which it cannot be carried on. 
The first indispensable requisite is, an adequate supply of gastric 
juice , and its thorough admixture with every particle of the j'ood 
on which it is to operate. The second is, a steady temperature of 
about 98° or 100« Fahr. ; and the third is, the gentle and con- 
tinued agitation of the alimentary mass in the stomach while di- 
gestion is going on. 
“ To test the reality of the solvent powers ascribed to the 
gastric juice. Dr. Beaumont withdrew from St. Martin’s stomach 
about one ounce of it, obtained after a seventeen hours’ fast, by 
introducing first a thermometer to induce the secretion, and then 
a gum-elastic, tube to carry it off. Into this quantity, placed in 
a vial, he introduced a piece of boiled recently-salted beef, weigh- 
ing three drachms. He then corked the vial tightly, and im- 
mersed it in water raised to the temperature of 100°, which he 
had previously ascertained to be the heat of the stomach when 
the secretion was going on. In forty minutes , digestion had 
distinctly commenced on the surface of the beef. In fifty 
minutes the fluid became quite opaque and cloudy, and the texture 
of the beef began to loosen and separate. In sixty minutes , 
chyme began to be formed. In one hour and a half, the muscu- 
lar fibres hung loose and unconnected,* and floated about in 
shreds. In three hours , they had diminished about one-half. In 
five hours, only a few remained undissolved. In seven hours , the 
muscular texture was no longer apparent ; and in nine hours the 
solution was completed. 
“ To compare the progress of digestion in the natural way 
with these results, Dr. Beaumont, at the time of commencing the 
experiment just described, suspended a piece of the same beef, 
of equal weight and size, within the stomach, by means of a 
