342 Observations on the Effects produced by 
observation. The application of a ligature round the choledoch 
duct is easily accomplished, and with very little suffering to the 
animal; so that any derangement in the functions of the viscera, 
which follows, cannot reasonably be attributed to the mere 
operation. The division of the stomachic ropes, or terminations 
of the eighth pair of nerves on the cardia of the stomach, and 
the ligature of the whole extremity of the pancreas, are opera- 
tions of much greater difficulty ; yet it has been ascertained that 
neither of these at all interfere with the conversion of the food 
into chyme, or that of the chyme into chyle. 
When an animal swallows solid food, the first change which 
it undergoes is that of solution in the stomach. In this state 
of solution it is denominated chyme. The appearance of the 
chyme varies according to the nature of the food. For example, 
in the stomach of a cat the lean or muscular part of animal 
food is converted into a brown fluid, of the consistence of thin 
cream ; while milk is first separated into its two constituent 
parts of coagulum and whey, the former of which is afterwards 
re-dissolved, and the whole converted into a fluid substance, 
with very minute portions of coagulum floating in it. Under 
ordinary circumstances, the chyme, as soon as it has entered 
the duodenum, assumes the character of chyle. The latter is 
seen mixed with excrementitious matter in the intestine; and 
in its pure state ascending the lacteal vessels. Nothing like 
chyle is ever found in the stomach ; and Dr. Prout, whose atten- 
tion has been much directed to the chemical examination of 
these fluids, has ascertained that albumen, which is the princi- 
pal component part of chyle, is never to be discovered higher 
than the pylorus. Now, in my experiments, which were made 
chiefly on young cats, where a ligature had been applied so as 
to obstruct the choledoch duct, the first of these processes, 
namely, the production of chyme in the stomach, took place as 
usual; but the second, namely, the conversion of the chyme 
into chyle, was invariably and completely interrupted. Not 
the smallest trace of chyle was perceptible either in the intes- 
tines or in the lacteals. The former contained a semi-fluid 
substance, resembling the chyme found in the stomach, 
