The mucous fluids are not the only ones that are thrown out, and are in this way excrementitious substances to the economy; this is the case with almost all the fluids separated from the mass of blood by secretion; this is evident as it respects the greatest part of the bile; probably the saliva, the pancreatic juice and the tears are also thrown out with the excrements, and their colour alone prevents them from being distinguished like the bile. I do not even know if, by reflecting on many phenomena, we might not attempt to establish as a general principle, that every fluid separated by secretion does not enter the circulation again, that this phenomenon belongs only to the fluids separated by exhalation, as those of the serous cavities, of the articulations, of the cellular texture, of the medullary organ, &c.; that all the fluids are thus either excrementitious or recrementitious, and that no one is excremento recrementitious as the common division implies. The bile in the gall-bladder, the urine in the bladder, the semen in the vesiculæ seminales, are certainly absorbed; but it is not the fluid itself which re-enters the circulation; it is only its most delicate parts, some of its principles which we do not exactly know, probably the serous and lymphatic part; this does not resemble the absorption of the pleura and other analogous membranes, in which the fluid re-enters the blood as it came out of it. That which is certain on the subject of the excretion of the secreted fluids is, that I have never been able to produce absorption of the bile by the lymphatics by injecting it into the cellular texture of an animal; it produces there inflammation and afterwards suppuration. We know that urine effused is not absorbed and that it destroys every part it touches, whilst that effusions of lymph and blood are easily discussed. There is as it respects the composition an essential difference between the blood and the secreted fluids. The exhaled fluids on the contrary, as the serum, in this respect resemble it very much.