Page:Proceedings of the Royal Society of London Vol 1.djvu/46

Rh ﬂexible membranaceous substance, very similar to the cortical part of some of the Gorgoniae; and in like manner slightly hardened by carbonate, mixed with a small portion of phosphate of lime.

From this mass of evidence we collect, in general, that the varieties of bone, shell, coral, and the numerous tribe of Zoophytes with which the last are connected, only differ in composition by the nature and quantity of the hardening or ossifying principle, and by the state of the substance with which this principle is mixed or connected; the gluten, or jelly, which cements the particles of carbonate or phosphate of lime, and the membrane, cartilage, or horny substance which serves as a basis, appearing to be only modiﬁcations of the same substance which progressively graduates from a viscid liquid. or gluten, into a gelatinous substance, which again, by increased inspissation, and by the more or less perfect degrees of organic arrangement, forms the varieties of membrane, cartilage, and horn, which it seems form the peculiar differences of the several species.

It is obvious that in this inquiry much depends upon an accurate investigation of the gluten, or jelly, so often mentioned as a principal ingredient in the substances under examination. This gave rise to the experiments on the analogous substances above mentioned, which led to a better acquaintance with the substance which now obtains the name of gelatin.

_ Not being allowed to enter into a. detail of these experiments, we shall only observe at present, that this gelatin is a component part of most of the animal substances above enumerated; that it varies in quality from a very attenuated jelly or mucilage, to that viscid substance called glue, the varieties of which also differ in solubility and tenacity : that it is present in various proportions, so that certain bodies, such as the cutis and cartilages of the articulations, seem to be entirely formed by it; while others, like nail, quill and tortoiseshell. can hardly be said to contain any; and that by its presence in various states and proportions, it may be regarded as the principal cause of those degrees of ﬂexibility, of elasticity and of putrescibility, so various in different parts of animals.

In all these substances, when all the gelatin they contained had been separated, either by repeated boiling in water, or by being steeped in dilute acids, 3. more insoluble substance remained of a very different nature from the gelatin, and which became the object of another extensive analysis. The results here led to the curious and important conclusion, that the substance known by the name of albumen is in fact the primary animal matter from which all the others, and even the gelatin and the animal ﬁbre, are ultimately derived, the formation of the two latter beginning with the process of sanguiﬁcation in the foetus, and the immense variety in the animal creation being deducible from the inﬁnite diversity and modiﬁcations in texture, ﬂexibility, elasticity, and other properties of the same substance composing the several parts which constitute the bodies of animals.