The second kind of cavities of nutrition belong especially to the texture of the cells of the bones. Thus they are seen wherever this texture abounds, in the extremities of the long bones, the circumference of the flat ones, and the whole superficies of the short ones. Their diameter is greater than that of the canal which goes to the medullary cavity; it is less than that of the canals of the compact texture. Their number is very considerable; I have counted a hundred and forty upon the tibial extremity of the femur, twenty upon the body of one of the dorsal vertebræ, fifty upon the os calcis, &c. In general this number is always in proportion to the quantity of the texture of the cells that the bone contains. Hence why there are but few on the flat bones of the cranium, why they are more numerous on the flat bones of the pelvis especially where this texture is abundant, as on the ischium, on the iliac portion of the circumference of the ilium, &c. By pouring mercury into the spongy texture, it runs out from all these foramina, and thus proves their communications. They are irregularly scattered wherever they are. They are not met with on the body of the long bones, because the body contains little or none of the texture of the cells. The third kind of canals of nutrition is only destined to the compact texture. It consists of an infinite number of little pores which the eye can clearly distinguish, and through which small vessels pass, that go to this texture. An evident proof that they do not go to the texture of the cells, is, that in the preceding experiment, the mercury never finds in them a way to escape externally. It is impossible to determine their number; it is prodigious in childhood. As the bones in old age become filled with calcareous substance, they are obliterated, and the vessels they contain become small ligaments, foreign to osseous nutrition, which continually grows weaker, and is soon annihilated, and allows necrosis to seize upon the bones, if general death does not prevent this partial death of the osseous system. ARTICLE SECOND. ORGANIZATION OF THE OSSEOUS SYSTEM. The peculiar texture of the osseous system forms in it the principal and predominant part, especially as we advance in age. The common organs are in much less proportion. I. _Texture Peculiar to the Osseous System._ The texture of the bones, like that of most of the other organs, presents itself under the aspect of fibres whose nature is everywhere the same, but which differently arranged, form two principal modifications; in the one, these fibres being more or less scattered, exhibit many cells; in the other being close to each other, they form a compact substance in which it is difficult to distinguish them. Hence two sub-divisions of the osseous texture, that with cells, and the compact. Authors admit a third one, the reticular; but this is included in the first. _Texture with Cells._