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appear, from the analysis of Vauquelin, to have a relation to the resinous secretions; and there are some substances derived from different species of animals, as civet, musk, and castor, which may be placed in the same class. We must also refer to this class the peculiar substance which was first pointed out as a distinct animal principle by Rouelle, and was afterwards more accurately examined by Thenard, and named by him osmazome. It was originally procured from the muscular fibre, of which it forms one of the component parts, and appears to be that ingredient upon which the peculiar flavour and odour of the flesh of animals principally depends. According to some experiments, of which we have the detail in three dissertations lately published at Tubingen, by Gsell, Gmelin, and Wienholt,'

5

3 Fourcroy, System, by Nicholson, v. ix. p. 451, et seq.; Thomson, Chem. v. iv. p. 523.

We have a valuable paper by Dr. Haygarth on this subject, the principal object of which is to point out the best means of dislodging it from the ear when it has accumulated there in an excessive quantity; we should be induced from his experiments to conclude that a considerable proportion of it consists of a mucous substance, depending, however, for its specific properties upon a body resembling the resin of the bile; Med. Obs. and Inq. v. iv. p. 198. et seq.

. 4 Thomson, Chem. v. iv. p. 441. et seq.; Thenard, Chem. t. iii. p. 777. et seq.

5 Thomson, Chem. v. iv. p. 425; Henry, Elem. v. ii. p. 465. 6 Berzelius, however, doubts whether osmazome is to be regarded as a distinct proximate principle; he seems to consider it as a compound of animal matter with lactate of soda; Ann, Phil. v. iii. p. 201. note.

7 Ed. Med. Journ. v. xii. p. 473. et seq.

osmazome is found in most of the component parts of the body, as well solids as fluids, although in very different proportions. It was found by Gsell to be much more copious in the muscles than in the bones and tendons, and in the muscles of old, than in those of young animals. Gmelin's experiments were particularly directed to the composition of the kidney; he examined this organ in the human subject, in the ox, and in the rat, and the result was, that a considerable proportion of osmazome was, in all cases, detected in the different parts of it, along with various neutral and earthy salts.

Weinholt extended his examination to other parts of the body, and found them all to contain certain portions of this substance. Some of the most important of his results are on the comparative quantity of osmazome, procured from blood as taken from different vessels; the greatest quantity was obtained from the vena portæ, a smaller quantity from the vena cava, and least of all from the aorta. He seems to consider the animal matter in the serosity as a compound of osmazome and urea, an opinion which nearly coincides with that maintained by Prevost and Dumas. This view of the subject, to a certain extent, countenances the idea of Berzelius, that the serosity consists of decomposed matter, which is carried into the blood-vessels, in order to be afterwards removed from the system, while it tends to throw some doubt upon the correctness of the

8

8 Ann. de Chim. et Phys. t. xxiii, p. 94.

deductions made by Prevost and Dumas from their experiments, so far as respects the theory of secretion generally."

The eighth and last class of secretions are the saline, a very numerous set of bodies, which are found dispersed over every part of the system, and more or less mixed with almost all its constituents. They consist of acids, alkalies, and neutral and earthy salts.

9 The observations of Jacobson referred to above, p. 368, on the comparative anatomy of the venous system of the abdominal viscera, tend to show, that there is some connexion between the functions of the liver and the kidney, and might lead us to suppose that these organs are both of them rather excrementitious than secretory. That there is some connexion between the functions of the liver and the kidney seems to be proved by a singular circumstance stated by Mr. Rose; Ann. Phil. v. v. p. 424..7; confirmed by Dr. Henry, Ibid. v. vi. p. 392, 3; that in hepatitis there is no urea secreted by the kidney. Should this be found to be a general occurrence, it would seem to indicate, that in some way or other, the secretion of the bile is a preliminary step to that of the urea, but we do not possess any data, either anatomical or pathological, which can enable us to determine how this preliminary change is effected.

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The following acids are generally recognized as entering into the composition of animal substances, for the most part, however, in combination with an alkaline or earthy basis; the phosphoric, the muriatic, the sulphuric, the fluoric, the lithic, the lactic, the benzoic, the carbonic, and the oxalic, as existing in certain species of urinary calculi. To these we may add some others of more doubtful existence, such as the rosacic and the amniotic; there are also other acids which we obtain in our examination of animal substances, as the prussic, and the mucic, which appear to be generated during the process. Soda, potash, and ammonia, are all found in the animal fluids, the soda alone in the uncombined state. Of the earths, lime is by far the most

The most important of these, both from the quantity in which it exists, and its uses in the system, is the phosphate of lime, which constitutes the earthy matter of the bones, giving them their hardness and solidity, and composing a large part of their substance; but, with the exception of the bones, the fluids generally contain more saline matter than the solids. A certain quantity of salts is always present in the blood, and it would appear that the class of albuminous secretions contain nearly the same kind of salts, and in the same proportion, and this, as I remarked above, without any exact relation to the quantity of animal matter. The proportion of saline matter that is attached to the solid albuminous secretions, and to the gelatinous, is much smaller; the pure oleaginous secretions appear to be entirely destitute of any saline impregnation, while, on the contrary, the compound oleaginous secretions contain it in considerable quantity. It is found still more plentifully in the resinous secretions, and more especially connected with the urea, in the urine, where we meet with the greatest variety of salts, and where, with the exception of the bones, the saline substances exist in the greatest proportion of any part of the body.

It has been supposed that a reference to the nature

abundant; magnesia is found in small quantity, and also silex. Sulphur, phosphorus, iron, and, according to Vauquelin, Nicholson's Journ. v. xv. p. 145, manganese, appear also to exist in some of the constituents of the animal body, which, although not properly saline, may be conveniently placed in this class, in consequence of their relation to the salts..... *

and quantity of the saline substances that are found in the secretions, might enable us to form a natural classification of them, which would throw some light on the mode of their production, and even on the nature of secretion in general. Upon a principle of this kind, Berzelius divided all these bodies into secretions and excretions, the first being always essentially alkaline, and the latter acid; but this, I conceive, would exclude many substances to which the title of secretion strictly belongs. It does not appear to me that we can lay down any arrangement of this description, which will apply to all the substances in question, but there may, perhaps, be a foundation for a division of them into four classes: 1. Those that are nearly without any mixture of salts; 2. Those which possess a definite quantity of salts, and this different from what exists in the blood; 3. Those containing salts, similar both in their nature and quantity to those in the blood; and 4. Such as contain salts different from those in the blood, and which are also variable in quantity. The fat, the saliva, the fluid discharged from the serous membranes, and the urea, may be taken as an example of each of these divisions. If we inquire in what way we are to connect the constitution of these substances with the supposed mode of their production, we may consider the two first, as the effect of proper secretion, where à substance that did not previously exist is elaborated by the action of the vessels; the third, of transudation,

View of Animal Chemistry, p. 61, 2.