Midler gives an account of a fluid which makes its appearance after a portion of the skin of a frog is removed from the muscles; this fluid he considers to he pure lymph ; he de scribes it as perfectly transparent and colourless, having a saline taste, but void of smell. Under the microscope he detected in it a number of colourless and spherical globules, about one fourth of the magnitude of the elliptical blood corpuscule of the same animal, a few of which were unavoidably mixed with this lymph. Muller also describes what he considers to be human lymph, obtained from a small fistulous opening on a man's foot, the remains of a wound received on the instep ; by pressure from the great toe towards the opening a transparent fluid could be made to transude; this fluid also contained colourless spherical globules, much smaller than the blood corpuscules. It, as well as that obtained from the frog, coagulated spontaneously, and appeared to possess the other properties of lymph. After coagulation had taken place in the fluid obtained from the man's foot, he observed that the globules were partly found in the clot, while some remained in the fluid surrounding the clot. In the horse's lymph examined by myself, all the globules were entangled in the clot.
The red colour of the contents of the tho racic duct, especially in the horse, has been remarked by most observers, but the cause of this redness has not been well ascer tained. Breschet says, in his Systeme Lym phatique, page 160 : " Ce qu'il eat etc in teressant surtout de determiner, c'est si is ma fibre colorante qui teint quelquefois le chyle, et meme la lymphe, y est dissoute, ou si elle affecte soit toujours, soit au moins quelque fois, la meme disposition que celle des globules du sang." I have frequently examined micro scopically this reddish fluid of the thoracic duct, and have invariably found it to depend upon the presence of red corpuscules of precisely the form and size of those of the blood. I believe that these red corpuscules are extraneous to the lymph, that their presence is accidental, and should be considered as a post-mortem occur rence. I would attribute their existence in the contents of the thoracic duct to the circum stance that very many lymphatics must be di vided with the other structures, before the tho racic duct or indeed any large lymphatic can be exposed; these divided lymphatics must necessarily have blood applied to their cut extremities ; the vessels being open receive the blood corpuscules, and convey them from all parts to the thoracic duct. This is not mere conjecture. I have seen the blood enter the divided vessels in the following experiment made for the purpose. On the under surface
of the liver of a horse recently killed I ob served some large lymphatics filled with a beautifully transparent fluid. I made an inci sion into the liver over these vessels, of course di viding them, and in a few seconds saw them con veying a reddish fluid towards the thoracic duct.
The lymph bears great resemblance to the liquor sanguinis both in its physical and che mical characters. Muller, who had observed that the blood of frogs will not coagulate when they are kept out of water in summer for eight or ten days, mentions the coincidence that when this is the case, the transparent fluid which he obtained by removing a piece of skin from a living frog, and which he conceived to be the lymph of the animal, was also incapable of spontaneous coagulation.
Leuret and Lassaigne give the following analysis of lymph obtained from the lympha tics of the neck in a horse : Water 925 Albumen .... . 57.36 Fibrine . 3.30 Chloride of sodium • Chloride of potassium 14.3• Soda ....
Phosphate of lime 1000.00 4Salivary matter, ozmazome, carbonates, sul. phates, muriates, and acetates of soda and potash, with phosphate of potash, have in addi tion been detected in the lymph by Tiedemann and Gmelin.
Chevreul analysed some lymph procured by Magendie from the thoracic duct of a horse after five days' abstinence. Its composition was as follows:— Water .... 926.4 Fibrine 4•2 Albumen .... 61.0 Muriate of soda 6.1 Carbonate of soda 1•8 Phosphate of lime Carbonate of magnesia 5 Carbonate of lime 1000.0 M. Magendie and M. Collard de Martigny have examined the lymph in animals, after de priving them altogether of sustenance ; up to the tenth or twelfth day the lymph was found in greater abundance, appeared to have more of the red tinge, and to be more consistent ; but after this period it diminished in quantity, be came more watery and had less of the rose tint. The latter physiologist rejects altogether the opinion entertained by some, that the lymph would assume a redder colour the longer the animal fasted.
The lymph is said to coagulate more readily after passing through the lymphatic glands, and the nearer it approaches the thoracic duct. I have not found this to be the case in so marked a degree as has been stated. I have collected lymph from the lymphatics of the intestines before they reached the glands, and from va rious parts of the body in which no glands are situated, and have invariably found the fluid to coagulate spontaneously, although if in small quantity it may shortly return to the liquid state.