=

D. The black residuum was now carefully dried and weighed, in order to constitute a check to the above. Its weight was 19:5 grains 78 per cent., indicating a loss of 1-60 in the abovementioned processes. This I considered as the pure colouring principle. It was of a fine full black colour, and possessed the shining appearance of powdered charcoal. It was insoluble in the muriatic and sulphuric acids, even when assisted by heat. Also in the acetic: Concentrated nitric acid acted on it readily, and with considerable energy, abundance of red fumes being emitted; and at length a partial solution, being formed of a very deep reddish brown colour. A solution of pure potash added to this solution produced no precipitate; but a solution of the subcarbonate of potash produced a slight one. A solution of caustic potash, assisted by heat, likewise effected a partial solution of this substance. Also caustic ammonia in a slighter degree. The colour of these solutions was of a deeper brown than that in nitric acid. The muriatic and sulphuric acids produced a slight precipitate when added to this alkaline solution, but not the nitric acid.

It burnt, without melting, with considerable difficulty, emitting the usual smell of burning animal matters, somewhat modified by a fishy odour. It left a very minute portion of reddish ashes, which proved to be a mixture of red oxide of iron, lime, and magnesia, the quantities in the order mentioned, that of the oxide of iron being greatest. Hence 100 parts of this substance contained

The carbonates of magnesia and lime, from their being so readily extracted almost entirely by the muriatic acid, appear to have been in a state of mechanical mixture only in this substance. The iron undoubtedly formed a component part of it, as it does in the colouring matter of the blood. The quantity I possessed was too small to enable me to make the investigation so complete as could be wished; though, from what has been said, it will appear to be chiefly characterized by its negative properties.

Mr. G. Kemp* has made some experiments on this substance in its recent state. He appears to have considered it as consisting of, or at least containing, albumen; but apparently without any very good reason. It appears to me, that all the effects of coagulation, precipitation by alcohol, mineral acids, metalline solutions, &c.,

* Nich. Journal, vol. xxxiv, p. 34,

described by him, did not depend upon albumen, but upon a species of mucus, which, probably, had he tried it, would as readily have been precipitated by acetic acid and heat, as by any of the mineral acids. If albumen had really existed in it, I see no reason why I should not have met with, at least, traces of it in the aqueous solution, (A) since it is well known that albumen may be dried at 'a low temperature, without injuring its properties of dissolving in water, or, as far as I know, any of its properties.* I cannot say, indeed, how the specimen I obtained was dried; but it had the appearance of having been dried spontaneously by simple exposure to the air. The properties of the colouring matter, as described by Mr. Kemp, do not differ materially from those above described. After all, however, it would be desirable to examine this substance in its recent state, as it appears to have undergone some changes in drying

This substance, from the length of time which it takes to subside in water, appears admirably contrived for the purpose of concealing the animal from his enemies, &c. A property also which, added to the permanent nature of its colour, must, as Mr. Kemp observes, render it valuable as an ink, or water colour.

ARTICLE IV.

Refutation of Mr. Walker's Claim to the Discovery of the Uses of the Cerebellum: with further Observations on Respiration. By

Dr. Cross.

SIP,

(To Dr. Thomson.)

Glasgow, April 8, 1815.

In the 27th number of your Annals of Philosophy there appeared a letter from one Dr. Leach, in which it is peremptorily asserted that Gall and Spurzheim have anticipated me in the discovery of the function of the cerebellum, and of the structure of the "spinal mass of nerves."

I may observe in addition to the above, that as far as my observation extends, albumen, such as it exists in the blood, is not found as a product of secretion, either by a mucous membrane, or glandular apparatus. I am aware that many substances have been called albumen by different chemists, which, as Berzelius first showed, were not entitled to the name; as for example, the mucus of the gall bladder, which appears to possess many of its properties. But this is precipitated by acetic acid, even without heat. It cannot therefore be albumen, since it is well known that a solution of albumen in acetic acid may be boiled without coagulation, and that prussiate of potash precipitates it from this state of solution, as was first shown, I believe, by the above mentioned excellent chemist, Ammonia also precipitates albumen from its solution in acetic acid; but this has the disadvantage of re-dissolving the precipitate, if added in excess. Hence acetic acid and prussiate of potash may perhaps be considered as the best tests of albumen at present known. The phosphoric acids, also, and, I believe, most of the other vegetable acids, like the acetic, do not coagulate albumen,

In the 28th number, Mr. Alexander Walker comes forward, strikes Dr. Leach off the field by giving a flat denial to his most unfounded assertion, and thrusts in a claim for himself to the discovery. Mr. Walker, in quoting from my letter, begins at the middle of a sentence, and thus makes me appear to deduce a conclusion from most insufficient data. Moreover, he merely quotes my first conjectures on the subject without giving the smallest hint of the decisive experiments to which they led. Genuine philosophy ought to expand the breast with candour.

I never before saw Mr. Walker's speculations on the nervous system, or knew that they existed. Had I seen the third volume of the Archives before I wrote to you, I would not certainly have claimed the discovery of the quadripartition of the spinal marrow. This discovery, although quite original on my part, belongs, from priority of publication, to Mr. Walker. Mr. Walker, however, has not anticipated me with respect to the sacral termination of the spinal marrow. I am the first, so far as my reading has gone, to lift off the cauda equina, and show the marrow terminating at the sacrum in a sharp point like the quill of a porcupine. This discovery rather militates against the old doctrine that the spinal marrow is just a bundle of nerves proceeding to and from the brain, which doctrine Mr. Walker has adopted. "The spinal marrow," he asserts, serves no other purpose than a nerve would have done in the same situation, although from its being protected by the canal of the vertebræ, and the productions of the cerebral membranes, it requires not the strong and more close investments which the nerves possess in order to protect them in their passage among moving organs." (Archives, vol. iii. p. 142.) I, on the contrary, view the cerebrum, cerebellum, and spinal marrow, down to the very point of this porcupine extremity, as one continuous organ, which may be styled the animal brain, while the cauda equina, and all the other animal nerves, are merely derivative.

I do not know what Mr. Walker means by quoting from the Archives about the cerebellum. His hypothesis regarding the cerebellum is, that it is the organ of volition; and he arrived at this same hypothesis by the following logical ratiocination. Because the situation of the cerebellum is opposite to the situation of the face, therefore the function of the cerebellum must be opposite to the function of the face; and it being an understood maxim in physiology that sensation is just directly opposite to volition, and as sensation resides in the face, so volition must reside in the cerebellum. This doctrine is said to be corroborated by this sapient consideration, "that as the organs of sense and the cerebellum are the first and the last portions of the nervous system, so sensation and volition are the first and the last of its functions." Although here the onus probandi lies with Mr. Walker, yet, to put this absurd and groundless hypothesis at rest, I may mention that volition ranks among the faculties of mind, whose organ is the cerebrum; and that affections of the cerebrum, while the cerebellum remains sound, produce

palsy, which I humbly submit is just a loss of volition. Mr. Walker's rude indigested hypothesis regarding the cerebellum must therefore fall to the ground. There is not one word from him about the cerebellum supplying the face with nervous energy. On the contrary, he makes out a direct opposition between the face and cerebellum. Had Mr. Walker, in his loose, dashing, conjectural way, thrown out a hint that perhaps the face might derive its nervous supply from the cerebellum, yet he would have had no claim to the discovery; for a discovery is not made until some kind of proof has been adduced; but it happens unfortunately for Mr. Walker that there is not even the smallest hint, from the beginning to the end of his tract, that could at all lead in the smallest degree towards the discovery. On the contrary, Mr. Walker has kept his face right away from the true direction, and looks earnestly down through the foramen magnum after the posterior columns of the spinal marrow as far as his eye can reach. Mr. Walker's volition is just about as far from the function of the cerebellum as Dr. Gall's amativeness.

My letter to you does not announce that I intend to make these discoveries the subject of my promised work. My announced subject is physiology and physiognomy, in which there are yet vast regions of terra incognita.

Notwithstanding the grand eulogy bestowed by Mr. Walker upon Dr. Spurzheim's work, I cannot help viewing it, with the exception of a little anatomical discovery, as a most fanciful production. The alchemists, as a friend of mine lately remarked when talking on this very subject, did actually improve the science of chemistry, although they have never yet found out the philosopher's stone. But enough on this subject at present, as I intend to take a future opportunity of making a few critical remarks on the Gallian doctrine.

In order to render this letter more worthy of insertion, allow me to say a little in amplification of the theory of respiration broached in my former letter. Of the three fundamental functions, respiration, nutrition, and propagation, only two, respiration and nutrition, are immediately connected with the life of the individual. The third is prospectively concerned with the continuation of the species, and indeed is not evolved till an advanced period of life.

What becomes of the food which is swallowed? Some goes to the growth of the body in youth, some in certain constitutions to obesity; some passes off in alvine, urinary, and cutaneous excretions, in cerumen, snot, &c; but all these excretions, with the largest allowance, do not nearly balance the quantity of food devoured. When it is moreover considered that some animals do not grow at all from birth till death; that all animals during a great part of life do not grow; that many great eaters never become fat; that in a state of health the excretions are trifling, and consist more of noxious than of nutritive materials, and that vegetables which absorb such an immense quantity of sap have no alvine, urinary, or such other excretion whatever, the inquirer becomes quite dissa

tisfied, and looks about for some more important function upon which the great quantity of chyle absorbed may be expended. Physiologists have traced the food through the alimentary tube and lacteal vessels into the subclavean vein; the chyle having got fairly into the circulation, is hurried, along with the blood and lymph returning from all parts of the body, to the lungs. All the blood, and all the chyle, and all the lymph, must perform the pulmonary circulation before they be admitted into the great systemic circulation. Now let us attend to what takes place in the lungs. According to your own calculation, as stated in the 737th page of the 5th vol. of your System of Chemistry, 3d edit. there are thrown out of the lungs by ordinary respiration in 24 hours no less than 40 000 cubic inches of carbonic acid, a quantity which contains about lb. avoirdupois of solid carbon. Whence is this carbon derived? The food is the only source from whence such a supply of carbon can be derived; while the blood is at once the grand reservoir of carbon to the lungs, and the vehicle of vitality to the body. By this conjoint view of respiration and nutrition, two mysteries are cleared up at once the source of the carbon, and the primary purpose of the food. The life of man has often been poetically compared to the burning of a fire, taper, &c. This poetical turns out a scientific analogy. As long as there is a supply of fuel, and a free admission of air, the animal fire continues to burn; the carbon of the fuel · combining with the oxygen of the atmosphere, and forming carbonic acid. Whenever the supply of fuel, or of atmospheric air, is interrupted, the fire declines; if the interruption is momentary, the fuel may rekindle; if the interruption has been too long, the fire goes out for ever. Thus we see that respiration is the great primary function for whose sake digestion was instituted; while all the excretions, like the ash-pits of a furnace, are things of merely secondary moment in the animal economy. To ensure a supply to respiration, carbon has been made the great substratum of vegetable and animal fabric-the chemical skeleton; so that when chyle is deficient, the very substance of the body is carried off to the lungs, and sacrificed on the shrine of respiration. No living organized body, from the primitive germ up to the adult stature, from the microscopic animalcule up to the whale, from the rudest lichen up to man, has ever been seen without organs of respiration. The cotyledons of vegetable seed must emit carbonic acid gas ere the radicle begins to send down its fibres into the earth; and if these cotyledons cease their respiration, and fail to become seminal leaves before the plumula rises and spreads its foliage to the heavens, the plant dies. If the pores of a fecund egg are stopped up, the hen may hatch upon it while she has heat in her body without bringing forth the chick. Nor does the chick, after it is fully formed, delay a moment to drive its bill through the shell for the free admission of air. The embryo, ere it begins to evolve, is connected to the uterus by means of a placenta as an intermediate agent between the foetus and the maternal lungs; and whenever the function of the placenta