1819.] and on the Blood in generat. 93 
These chemists agree in representing its properties as more 
imperfect and ill defined than those of chyle taken from the 
thoracic duct. That examined by Emmert and Reuss, when 
compared with chyle taken from the thoracic duct, was found to 
undergo spontaneous coagulation much more imperfectly, Its 
colour was white, with mmute yellow globules swimming in it. 
But in a few hours there was observed in it a little reddish mass 
swimming in a yellowish fluid, which, after some days, disap- 
peared, and assumed the form of a sediment at the bottom of the 
vessel. The specimen examined by Vauquelin was white and 
opaque like milk, and it contained a coagulum equally white and 
opaque. This coagulum was considered as imperfectly formed 
fibrin ; and in the chyle examined by Emmert and Reuss, con- 
stituted about one per cent. of the whole fluid. Both specimens 
also were found to contain albumen, the usual salts of the blood, 
and also a peculiar principle, the properties of which will be 
considered hereafter. 
Chyle from the thoracic duct has been often examined, and 
with very similar resuits. If an animal be killed a few hours 
after having taken food, and immediately opened, and the 
thoracic duct pierced, the chyle being now in a perfectly fluid 
state will flow out readily. Its colour at this time is nearly 
white. Its taste faintly saline and sweetish. Its smell peculiar; 
it has been compared by Emmert and Reuss to that of the . 
ontpua virile. In aperiod of time somewhat different in different 
instances, but generally in a few minutes, it begins to assume a 
gelatinous appearance, and to undergo coagulation ; the colour 
also, if it has been exposed to the air, changes to a faint red, or 
pink. The time requisite to produce the maximum effect of 
these spontaneous changes is different; sometimes an hour 
appears sufficient; generally, however, a much longer time is 
necessary. In this coagulated state, and often many hours, or 
even days after it has been removed from the body, it has, in 
every instance in which I am acquainted, been examined by 
chemists ; and the following observations, therefore, are to be 
understood to apply to it in this condition only. 
It would be loss of time to mention the opinions of the older 
physiologists in chyle. All the modern chemists have considered 
it as very analogous to the blood. The experiments of Emmert 
and Reuss and Vauquelin, gpave-monteiaed, establish this point 
in the most satisfactory manner; and those of others to the same 
effect might be mentioned if necessary. I shall only, therefore, 
detail a very few experiments. The most recent examinations of 
chyle are those of Dr. Marcet * and myself, of the chyles of two 
dogs, one of which had been fed entirely on vegetable food, the 
other on animal food. The experiments were made now upwards 
* * See Med. Chirurg. Transactions, vi, 618, 
