1819.

num.

and on the Blood in general.co

d

21

distance of about six inches from the pylorus, after which it diminished; and at the distance of 24 inches from the pylorus, it was barely perceptible. The contents of the ileum were of a greenish colour, and consisted of a greater proportion of the excrementitious part of the food than the contents of the duodeNo traces of albuminous matter were found in this portion of the intestinal canal. The cœcum in this animal is very large, and in the present instance was nearly full of a dark brown pultaceous mass, of a feculent odour, and which yielded no traces of albumen. The colon and rectum contained dry brown and hard scybala, apparently consisting of little more than the insoluble parts of the food and some biliary matter. None of the contents of the intestinal canal, from the pylorus downwards, were sensibly acid, or alkaline, nor did they appear capable of coagulating milk.

12

Very similar phenomena were observed in other instances. But when the animal was opened at a longer period after feeding, I generally found much stronger evidences of albuminous matter, not only in the duodenum, but nearly throughout the whole of the small intestines. The quantity, however, was generally very minute in the ileum; and where it enters the cœcum, no traces of this principle could be perceived. The general appearances also of the contents of the upper parts of the small intestines were always very similar to those above described; that is to say, they were of a yellowish colour, and of a ropy or glairy consistence, and mixed with some insoluble. and excrementitious matter. In the ileum in general the colour, was more green, the consistence firmer, and the proportion of excrementitious matters greater. In the cœcum there was always a great collection of feculent matter, which was uniformly similar in all its properties to that before described. The contents of the colon and rectum also were precisely similar in their appearances and properties to those above-mentioned..

Examination of the duodenal Contents of the Pigeon and Turkey. The pigeon was the same as that employed in observing the phenomena of digestion. Just at the commencement of the duodenum there were numerous air bubbles which exhibited the appearance of having been elicited by effervescence from the contents of the stomach upon their first entry into the intestine. The colour of the contents of this part of the intestine was greenish yellow, and their consistence was thin and glairy, with a mixture, as in the instance of the other animals above-mentioned, of some excrementitious matter. Near the pylorus, faint traces only of albumen were observed; but the quantity increased to about the distance of six inches, and afterwards rapidly diminished; and at 12 inches from the pylorus, no traces of this principle were perceptible; and here the alimentary matters assumed a browner colour and firmer consistence, and appeared to be altogether excrementitious,

The contents of the duodenum of the turkey have been examined by Dr. Marcet. He describes them as yielding abundant traces of albumen, and states that on being burned, they left a saline residuum of about six parts in a thousand of the original mass, amongst which the presence of iron, lime, and

an alkaline muriate was clearly ascertained."

Examination of the duodenal Contents of the Tench and Mackerel. From my being unable to procure fish in their natural state, my examinations of these animals have not been so satisfactory as could be desired. In the upper portion of the intestinal canal of the tench, which had been kept, as before observed, for some time in an unnatural state, no traces of an albuminous principle could be perceived; but lower down, where the alimentary matter was more abundant, I thought some traces of this principle were perceptible. In this animal, none of the substances found in the canal were sensibly acid, or alkaline, nor coagulated milk. In the mackerel, the contents of the duodenum and upper intestines very closely resembled those of the stomach, both in their appearance and properties, except that they were of a more glairy consistence, especially about the pyloric coca, and gave some faint indications of what I considered as an albuminous principle.

Properties of the Chyle.-I now proceed to describe, as far as they are known, the properties of the chyle in three different stages of its progress towards the sanguiferous system; namely, as it exists in the absorbent vessels, or lacteals, near the intestines, as it exists in the same vessels near the thoracic duct, and as it exists in the thoracic duct itself.

Owing to the minuteness of the lacteal vessels, and the consequent difficulty of collecting their contents in any quantity, the properties of the chyle, as it exists immediately after it has been absorbed from the intestines, are but imperfectly known. In the mammalia, it is opaque, and white like milk. In birds and fishes, on the contrary, it is nearly transparent and colourless. The only examinations of chyle in this state of its formation, that I am acquainted with, are those of Emmert and Reuss, which were made upon the chyle of the horse. It differed from perfect chyle taken from the thoracic duct, in being more white and opaque, in undergoing spontaneous coagulation much more slowly and imperfectly, and in not assuming a reddish colour on exposure to the air: hence it appeared to contain a very small proportion only of a principle analogous to fibrin, or, at least, this principle existed as yet in a very imperfect state, and no colouring principle.

Chyle from the sublumbar branches of horses has been examined by Emmert and Reuss, and likewise by Vauquelin.+

* See Annales de Chimie, tom. 1xxx, p. 81.

+ See Annales de Chimie, tom, lxxxi. p. 113; also Annals of Philosophy, ii, 220,

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 minute 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, disappeared, 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, constituted 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 results. 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 nipua virile. In a period 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, above-mentioned, 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 ehyle 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.

four years ago, at the request of Mr. Astley Cooper; and the chyles which I examined were, I believe, taken from the same two dogs, the contents of whose duodena have been described a former part of this paper.

Chyle of a Dog fed on Vegetable Food.—This is described by Dr. Marcet as appearing a short time after being collected in the form of a semitransparent, inodorous, colourless fluid, having but a very slight milky hue, like whey diluted with water. Within this fluid there was a coagulum, or globular mass,

also semitransparent, and nearly colourless, having the appearance and consistence of albumen ovi, or of those gelatinized transparent clots of albuminous matter which are sometimes secreted by inflamed surfaces. This mass had a faint pink hue, and minute reddish filaments were observed on its surface," To this description I have nothing to add, except that the specimen I examined did not sensibly affect litmus, or turmeric papers, ina any state, nor coagulate milk. Dr. Marcet's further observations also agree with my own. He found that the coagulum, when separated from the serum, parted readily with its serosity, or fluid portion, and was at length reduced to a very small size. The sp. gr. of the serum he found to be in different instances 1-0215 and 1022. He appears to have considered the serum as well as the coagulum to have contained albumen. The portion of solid matter, including salts, varied in different specimens of the chyle from 4-8 to 7:8 per cent. The proportion of saline matter was very uniformly about 0-92 per cent. 9olored doidw 9o8ly Chyle of a Dog fed on Animal Food.-Dr. Marcet's description of this species of chyle agrees also with my own observations. He describes it as resembling the last, except that instead of being nearly transparent and colourless, it was white and opaque like cream. The coagulum was also white and opaque, and had more distinct pink hue, with an appearance not unlike that of very minute blood-vessels. The coagulum, as in the former instance, gradually yielded further quantities of serous fluid till nothing remained but a small quantity of a pulpy opaque substances in appearance somewhat similar to thick cream, and containing

Pearabules, besides the red particles above noticed. The

residue of the coagulum became in the course of three days quite putrid, whilst that obtained from vegetable chyle in a similar manner had not yet begun to undergo that process." The serous portion on standing assumed a creamy-like appearance on its surface. Its sp. gr. and other properties were similar to those from vegetable food. It left a quantity of solid matter, including from 70 salts, varying in different specimens from 70 to 9.5 per cent. Oto The proportion of saline matter were the same as before.

The following are the results of my examinations of these two varieties of chyle:

Nearly the same modes of operating were adopted in the examinations of these specimens of chyle as in those of the chymes, formerly described; thus,

The quantity of water was ascertained, as in the former instances, by evaporating a known weight of the perfect chyle to dryness on a water-bath. The coagulum of the chyle was repeatedly washed with cold water till it ceased to give off any thing to that fluid; the remainder was a small portion of a substance differing in very slight particulars only from the fibrin of the blood. One of the chief of these differences was its greater difficulty of solubility in dilute acetic acid. It was, therefore, considered as fibrin.

ad

To the serous portion was added dilute acetic acid, and heat applied till the mixture boiled. A copious precipitation took place, which, therefore, was not albumen. It differed also from the caseous principle of milk, since it was readily and completely precipitated by the oxymuriate of mercury. It was named incipient albumen, and its nature will be more fully considered hereafter, but

After the above principle had been removed by filtration, prussiate of potash was added to the acetic solution. A copious precipitate fell, which was considered as albumen.

In the serum of the vegetable chyle there appeared a trace of what was considered as sugar of milk. This was not observed in the serum of the animal chyle.

In both chyles, but especially in that from animal food, there was a distinct trace of an oily substance.

The saline matters consisted chiefly of the alkaline muriates, with traces of a sulphate, and, perhaps, of a lactate; but of this last I am not certain.

92

The chyles of birds, fishes, and the inferior animals, have not, as far as I know, been examined. Their properties, therefore, at present, are entirely unknown, which is much to be regretted.