The analyses of M. Lecanu' are generally regarded as among the best. Blood obtained by him from two stout healthy men was found to be composed as follows:

On these analyses, Dr. Prout has remarked, that gelatin is never found in the blood, nor any product of glandular secretion; and he adds, that a given weight of gelatin contains at least three or four per cent. less carbon than an equal weight of albumen. Hence, the production of gelatin from albumen, he conceives, must be a reducing process. We have seen, under the head of Respiration, what application he makes of these considerations.3

Researches on the ashes of the blood by Enderlin,' in the laboratory of Giessen, give the following as the quantitative analysis in 100 parts from human blood:

1 Annales de Chimie et de Physique, xlviii. 308, and Journal de Pharmacie, Sept., 1831.

2 Bridgewater Treatise, Amer edit., p. 280, Philad., 1834.

3 For the methods of analyzing the blood, see Simon, op. cit., p. 166.

Annalen der Chemie und Pharmacie, Marz und April, 1844, cited by Mr. Paget, in Brit.

and For. Med. Rev., Jan., 1845, p. 255.

It has been inferred, from these analyses, that the albumen of the blood is not in the form of an albuminate of soda, nor of a combination with carbonate or bicarbonate of soda, but in combination with the alkaline tribasic phosphate, and chloride of sodium,—the former salt possessing, in a high degree, the power of dissolving protein compounds and phosphates of lime, and probably being the solvent of those constituents in the blood. Dr. John Davy,' however, thinks, that even admitting the accuracy of Enderlin's results, the propriety of applying them to the condition of the alkali in liquid blood may be questioned. Carbonate of soda, he observes, is decomposed when heated with phosphate of lime; and when added in small quantity to blood is not to be detected in its ashes. This may account for its not having been found there. Were the opinion, referred to, correct, an acid added to blood or its serum, after the action of the air-pump, ought not on re-exhaustion to occasion a farther disengagement of air; but Dr. Davy finds that it does. This and other results induce him to give the preference to the conclusion, that blood contains sesquicarbonate of soda.

M. Dutrochet believed, that he had formed muscular fibres from albumen by the agency of galvanism; and supposed, that the red corpuscles of the blood formed each a pair of plates, the nucleus being negative, the envelope positive; but Müller has shown, that all the appearances, which he attributed to different electric properties of the blood, are explicable by the precipitation of the albumen and fibrin in consequence of the decomposition of the salts of the serum and of the oxidation of the copper wire used in the experiments, both the decomposition of the salts and the oxidation of the copper being the usual effects of galvanic action. With the galvanometer he was unable to discover any electric current in the blood; and he perceived no variation in the needle of the multiplicator, when he inserted one wire into an artery of a living animal, and the other into a vein.

Lastly-Interesting experiments and observations on the blood were published several years ago by Dr. Benjamin G. Babington. The principal experiment was the following. He drew blood in a full stream into a glass vessel filled to the brim, from the vein of a person labouring under acute rheumatism. On close inspection, a colourless fluid was immediately perceived around the edge of the surface, and after a rest of four or five minutes, a bluish appearance was observed forming an upper layer on the blood, which was owing to the subsidence of the red corpuscles to a certain distance below the surface, and the consequent existence of a clear liquor between the plane of the corpuscles and the eye. A spoon, previously moistened with water, was now immersed into the upper layer of liquid, by a gentle depression of one border. The liquid was thus collected quite free from red corpuscles, and was found to be an opalescent, and somewhat viscid solution, perfectly homogeneous in appearance. By repeating the immersion, it was collected in quantity, and transferred to another vessel. That

Proceedings of the Royal Society of Edinburgh, vol. ii. No. 26, for 1845.

2 Handbuch, u. s. w., Baly's translation, p. 133.

3 Med-Chirurg. Transact., vol. xvi., Part 2, Lond., 1831; and art. Blood (Morbid Conditions of the) in Cyclop. Anat, and Physiol., Lond., 1836.

which Dr. Babington employed was a bottle holding about 180 grains, of globular form, with a narrow neck and perforated glass stopper. The solution with which the globular bottle was filled, though quite homogeneous at the time it was thus collected, was found, after a time, to separate into two parts, viz., into a clot of fibrin, which had the precise form of the bottle into which it was received, and a clear serum, possessing all the usual characters of the fluid. From this experiment, Dr. Babington inferred, that buffed blood, to which we shall have to refer under another head, consists of only two constituents, red corpuscles, and a liquid to which he gives the name liquor sanguinis-plasma of Schultz-so called by him, because he esteems it to be the true nutritive and plastic portion of the blood, from which all the organs of the body are formed and nourished.

It has long been observed, that the blood of inflammation is longer in coagulating than the blood of health, and that the last portion of blood drawn from an animal coagulates quickest. The immediate cause of the buffy coat is thus explained by Dr. Babington. The blood, consisting of liquor sanguinis and insoluble red corpuscles, preserves its fluidity long enough to permit the corpuscles, which are of greater specific gravity, to subside through the liquor sanguinis. At length, the liquor sanguinis separates, by a general coagulation and contraction, into two parts; and this phenomenon takes place uniformly throughout the liquor. That part of it, through which the red corpuscles had time to fall, furnishes a pure fibrin or buffed crust, whilst the portion into which the red corpuscles had descended furnishes the coloured clot. This, in extreme cases, may be very loose at the bottom, from the great number of red corpuscles collected there, each of which has supplanted its bulk of fibrin, and consequently diminished its firmness in that part. There is, however, with this limitation, no more fibrin in one part of the blood than another. Researches by Mr. Gulliver1 would seem to show, that the rate at which the red corpuscles sink in a fluid may give a very incorrect measure of its tenuity, since they subside much slower in serum, or in liquor sanguinis made thinner and lighter by weak saline solutions, than in the same animal fluids made thicker and heavier by gum. The blood, too, may have its coagulation retarded, whilst it is thinned and reduced in specific gravity; and yet no buffy coat appear. The greater aggregation of the corpuscles, observed by Mr. T. Wharton Jones, and subsequently in his experiments, seemed to him to be connected with the accelerated rate of subsiding; as it was prevented or reversed by salts, which dispersed the corpuscles, and increased by viscid matters, which increased the aggregation. It is a well-known fact, that the shape of the vessel into which the blood is received influences the depth of the buff. The space, left by the gravitation of the red corpuscles, bears a proportion to the whole perpendicular depth of the blood, so that in a shallow vessel scarcely any buff may appear, whilst the same blood in a deep vessel would have furnished a crust of considerable thickness; but Dr. Babington asserts,

1 Dublin Med. Press, Dec. 11, 1844.

Edinburgh Med. and Surg. Journal, Oct., 1843, p. 309.

that even the quantity of the crassamentum is dependent, within certain limits, on the form of the vessel. If this be shallow, the crassamentum will be abundant; if approaching the cube or sphere in form, it will be scanty. The difference is owing to the greater or less distance of the coagulating particles of fibrin from a common centre, which causes a more or less powerful adhesion and contraction of those particles. This is a matter of practical moment, inasmuch as blood is conceived to be thick or thin, rich or poor, in reference to the quantity of crassamentum; and pathological views are entertained in consequence of conditions, which, after all, may depend not perhaps on the blood itself, but on the vessel into which it is received.

To remove an objection, that might be urged against a general conclusion deduced from the experiment eited,-that it was made upon blood in a diseased state,-Dr. Babington received healthy blood into a tall glass vessel half filled with oil, which enabled the red corpuscles to subside more quickly than would otherwise have been the case. This blood was found to have a layer of liquor sanguinis, which formed a buffy coat, whilst a portion of the same blood, received into a similar vessel, in which there was no oil, had no buff. Hence, it appeared, that healthy blood is similarly constituted as blood disposed to form a buffy coat, the only difference being, that the former coagulates more quickly than the latter. Dr. J. Davy,' however, has observed, that inflammatory blood, in some instances, does not coagulate more slowly than healthy blood, and as from the experiments of Professor Müller2 it would appear that the presence of fibrin in the blood favours the subsidence of the red particles, Müller was led to infer, that the formation of the buffy coat may arise from the blood containing a larger quantity of fibrin, which the blood of inflammation is known to do. So that the principal causes, he thinks, of the subsidence of the red particles and the formation of the buffy coat in inflammatory blood, appear to bethe slow coagulation of the blood, and the increased quantity of fibrin. The most correct view, however, is, perhaps, that of M. Andral,3 that the essential condition of the buffy coat is an increase in the quantity of fibrin in proportion to the red corpuscles. Hence, if there be an absolute increase of fibrin, the red corpuscles remaining the same, as in inflammation; or, if there be a diminution in the proportion of the red corpuscles, the fibrin remaining the same, as in chlorosis, the buffy coat may result; provided only there be-as there probably always is under such circumstances-a greater aggregation of the corpuscles.

An interesting fact connected with this subject has been noticed by Mr. T. Wharton Jones. If a single drop of inflammatory blood be examined by the microscope, it will be seen that the red corpuscles have an unusual attraction for each other, which occasions them to coalesce in piles and masses, as in the second marginal illustration, leaving wide interspaces for the fibrin, lymph-corpuscles, and serum. It is probable, too, that there is an increased attraction between the

1 Philosophical Transactions, for 1822.

2 Op. citat., p. 117.

3 Hématologie Pathologique, p. 75, Paris, 73, or Meigs's and Stille's translation, Philad., 1844. Edinburgh Medical and Surgical Journal, Oct., 1843, p. 309.

particles of the fibrin, which will account for the firmer clot of the blood of inflammation.

The fact of a single drop of blood being sufficient to indicate the character of the whole mass may be important in cases where a doubt exists as to the propriety of bleeding to any

extent.

It is proper to remark, that recent researches by Mulder1 have led him to infer, that the buffy coat does not consist of true fibrin, but is a compound of a binoxide of protein, which is insoluble in boiling water, and a tritoxide, which is soluble. These oxides Mulder comprehends under the name oxyprotein.

Healthy and in Inflamed Blood.

a. Healthy blood. b. Inflamed blood.

It may, also, be remarked, that in all expe- Aggregation of Corpuscles in riments on the horse, whenever the blood flows from an opened vein in a continuous stream, with a sufficiently strong jet, and is received into a vessel that is neither too shallow nor too wide, the upper part of the clot is instantly found occupied by a white mass, which perfectly resembles the buff of the blood of man. Such was the result of the observations of MM. Andral, Gavarret, and Delafond.2 It need scarcely be said, that venous blood, composed as it is in part of the products of heterogeneous absorption, must differ in its character in the different veins. In its passage through the capillary or intermediate circulation, the arterial blood is deprived of several of its elements, but this deprivation is different in different parts of the body. That, for example, which returns from the salivary glands, must vary from that which returns from the kidneys. In the blood of the abdominal venous system, the greatest variation is observed. Professor Schultz has inquired into the chemical and physiological differences between that of the vena portæ and of the arteries and other veins. He found, that it is not reddened by the neutral salts, or by exposure to the atmosphere, or to oxygen; that it does not generally coagulate; contains less fibrin; proportionably more cruor, and less albumen; and has twice as much fat in its solid parts as that of the arteries and other veins; the proportions being as follows:

Simon, in his researches, also found a much less proportion of fibrin, and a larger of fat and of colouring matter. The fat he ascribes to the fluids produced during the act of digestion, which are conveyed into the portal vein. The subject of the changes produced on the portal

1 Annalen der Chemie, u. s. w., Bd. xlviii., Heidelb., 1843; cited by Mr. T. Wharton Jones, in Brit. and For. Med. Rev., July, 1844, p. 259.

Essai d'Hématologie Pathologique, p. 27, Paris, 1843.

3 Rust, Magazin für die gesammt. Heilkund. Bde. 44, H. i., and Lond. Lancet, Aug. 10, 1839, p. 717.

Animal Chemistry, Sydenham Society edition, p. 208, Lond., 1845.