That hydatids _may_ be formed on a cancerous gland, I shall not dispute; but that they are generally to be met with, or are in any respect essential to the disease, I cannot admit. In all the cancerous breasts, testicles, and tumors, which I have examined, I never saw any thing which could be considered distinctly as a hydatid; so that I suspect, that under this name have been described the small cancerous abscesses, with thick cartilaginous sides, which we so universally meet with in schirro-cancerous glands. We likewise find cancer take place in circumstances in which no hydatids can be found. Thus, for instance, a cancerous wart being knocked off the face, a cancerous ulcer is produced; but no hydatid is to be found at the base of the wart to produce this. When cancer has continued some time, it was believed that the matter was absorbed, taken into the blood, and that all the humours were speedily assimilated; and it was by this absorption and assimilation that they explained the fatal and rapid progress of relapses, after an apparent cure had been obtained. That matter is absorbed, is an undeniable fact; but the only effect which is produced by this, is on the lymphatic glands[125], which intervene betwixt the sore and the heart; for, beyond these, the matter does not pass qua virus, but is changed in its nature and properties, as is the case with every other part or production of the animal, which is absorbed and formed into part of the blood. Neither cancerous matter, nor variolous matter, nor syphilitic matter, ever are formed in the blood, or ever can enter into it, unless by means of an wounded vessel. This point I shall consider more fully, when I come to treat of the venereal inflammation. Here I shall only observe, that were the reverse true, then the contagious matter must pass through every gland, and every portion of the human form, in as much as the blood circulates in every point; and, therefore, every spot should become diseased, and every part, in the same circumstances, should become diseased at the same moment[126]. Disease is not spread in the living system mechanically, by the absorption of matter, which is conveyed over the whole body, but by the sympathetic connection of parts, which has been already explained, and which will afterwards be farther illustrated. It is in consequence of this, that a distant part shall become diseased, and yet all the rest remain healthy; and even where every part becomes affected, and a general disease is suddenly produced from a local sore, as, for instance, in small-pox, there is no diffusion of matter, nor is it ever conveyed beyond the lymphatic glands.