These experiments induced me to try some with the saliva, and I obtained the same result from them; only the languid state that succeeded the injection was less evident. I afterwards made use of nasal mucus suspended in a sufficient quantity of water, for it can hardly be dissolved in it. Finally urine itself was many times injected, not that which comes immediately from drink and is only aqueous, but that which is of slow formation. In this experiment the dogs have been sicker, but only one died, and that happened on the seventh day. I have many times repeated it, on account of that which I performed three years ago; the same result has always taken place, which makes me think that being but little used at that time to make experiments, I introduced by accident a bubble of air through the syringe, which is sufficient to produce the death of the animal. A question then is evidently settled by the experiment. The secreted fluids, though destined to be thrown out in the natural state, can re-enter the circulation, without causing the death of the animal, which is only more or less affected according to the nature of the fluid injected. Whether the bile circulates or not with the blood in bilious fevers, I have not examined; but it certainly can circulate with it after having been absorbed in its canals. I do not doubt but that in purulent reabsorptions, the pus circulates in its natural state in the sanguineous system; I confess that I have not made experiments upon the injection of this fluid, but I intend to immediately. We exaggerate every thing. No doubt the solids in which the vital forces are especially inherent, are particularly affected in diseases; but why should not the fluids be affected also? Why should we not seek in them causes of disease as well as in the solids? There are cases in which these are primarily affected, and in which the fluids are so in consequence; thus in cancer, in the affections of the liver, the spleen, &c. in most organic lesions, the various yellowish, grey, brown and even greenish shades of the face, are an index of the consecutive alterations which the fluids experience in their colour and consequently in their nature. In other cases the affection commences with them; as when the venom of the viper is introduced into the blood, as when reabsorption of pus takes place from external abscesses, or in phthisis, and as when there is absorption of various contagious principles. There is no doubt that the different substances which can be introduced with the chyle into the blood, may be the cause of various diseases. Is it not the blood which carries to the brain the narcotic principles which produce sleep? does it not carry turpentine and cantharides to the kidneys, mercury to the salivary glands, &c.? Inject opium, wine, &c. into the veins, and you will stupify the animal the same as if you had given them by the stomach.