The oil or unctuous soft solid which is now ascertained to be one of the constituents of healthy blood,* is liable to morbid increase under various forms of disease. Morgagni cites two cases of malignant fever in which the serum was milky. Hewson, besides enumerating in stances to be met with in authors, gives three cases sent him by medical friends : one of amenorrhoea with dyspepsia and vicarious dis charge of blood by vomit and stool ; another of violent and continued epistaxis, and a third of dyspepsia with slight asthma. In all three cases there were symptoms of plethora ; but milky serum is by no means necessarily connected with this state. The most marked instance that I have met with was in a case of diabetes, where bleeding was several times repeated at long in tervals, and on each occasion the same morbid condition ofserum was observed. This was quite opaque, and nearly as white as milk; and on standing for a few hours, a film of mattter re sembling cream covered the surface. The clot could not be seen when it was scarcely a tenth of an inch beneath the surface. It had a firm, very thick, white coat of fibrine, and the red particles were almost diffluent beneath. The patient, a female, could not be called ple thoric, having been the subject of her emaci ating complaint more than a year and a half. Milky serum, though of a far less marked cha racter, having occurred in persons who have been bled shortly after making a hearty meal, the notion has been entertained that it is owing to the passage of liquid chyle into the circu lation. This was Haller's opinion, while others have attributed its appearance to admixture of fat. To the former notion it may be objected, that whereas it is certain that the milky appear ance of serum is owing to the presence of oily particles, it is very doubtful, from the discord ant opinions of eminent chemists, whether the chyle contains more oily matter than the blood itself. Berzelius, indeed, makes its solid part to consist of more than twenty-one per cent. of fat, and Raspail considers it as differing little from milk. Prout, however, whose analysis is adopted by Turner, only admits an unappre ciable trace of oily matter in chyle, and makes its composition differ little from blood ex cept as respects the absence of red particles. In milky serum the oil exists in superabun dance at the expense of the albumen, which, in all the specimens I have examined, has been remarkably deficient in proportion, its specific gravity varying from 1.019 to 1'024. This cir cumstance naturally leads to a question whether this oil may not owe its origin to some chemical change in the albumen itself, of which it seems to supply the place. The ' remarkable blood' described by M. Caventou,* and alluded to by M. Raspail, t which was evidently nothing more than blood with milky serum, affords ad ditional ground for supposing that such a change takes place. " This blood issuing from the vein was turbid, of a pale dirty red colour, and became marled and of a whitish red as it cooled in the basin, and some drops which fell on the floor assumed this colour in a few seconds, and looked like drops of chocolate made with milk. After half an hour a coagulum of moderate size was formed in it, which floated in a large quantity of a white opaque fluid ex actly like milk." Raspail, who had evidently never seen a marked example of milky blood, gives the following fanciful explanation of the appearance. " Under the influence, or in the absence of one of the causes which together produce the circulation, an acid had been formed, which, saturating the alkaline men struum of the albumen, had caused it to coagu late. Now this irregular coagulation could not take place without disguising the colour of the blood and rendering it rose-coloured, while it would give the serum the appearance of milk." If the albumen had really been coagulated by an acid, a distinct clot would not have been formed by it, but a curdled precipitate ; nor would the serum have borne any resemblance to milk. But what is important as confirming my view respecting the conversion mentioned above, M. Caventou, to his great astonishment, could not find any albumen in the milky serum here described. The probability of this change is heightened by the consideration that some thing analogous must necessarily occur in the formation of true milk, the oil of which, when separated as butter and melted to clarify it from curd, remarkably resembles the oil of milky serum.
The attention of pathologists to the salts of the blood, which, considering the visible effects they produce on this fluid, had been strangely neglected, has of late years been roused by the observations of Dr. Stevens, who certainly may claim the merit of having advanced our know ledge of facts on this subject. It appears that in the last stages of tropical fevers the saline ingredients of the blood are so much diminished that they are no longer capable of giving a red colour to the hwmatosine. The black blood that is found in the heart after death from either the climate fever or the African typhus, remains black even in an atmosphere of pure oxygen, hut it instantly changes colour when we add it to a clear fluid that contains even a small portion of any neutral salt. Nor is it in fever alone that this deficiency of salts is observed. Dr. O'Shaughnessy has shewn that it likewise exists in malignant cholera, and it is probable that in sea-scurvy, and in those analogous dis eases produced by want and unwholesome nourishment, a similar state occurs.
The saline matters may be in excess as well as in defect, and this is marked by excitement of the circulating system, and either local de terminations or general febrile disturbance. The stimulant effect of saline springs has been known time out of mind, while the thirst and heat pro duced by the too copious use of common salt is in every body's experience. If we couple these facts with the certainty that the neutral salts will pass unchanged through the circu lation so as to admit of detection in the urine, we may infer that their superabundance in the bond is not only a possible, but, in all proba bility, a frequent occurrence. They are occa sionally found after death deposited in a crys talized form, as was observed by Sir Everard Home, who, in dissecting an aneurismal tumour, found a mass of crystars, which were analyzed by Mr. Faraday, and are stated to have been salts usually met with in the blood.
Having thus concluded such remarks as the present state of our knowledge has enabled me to offer respecting the morbid changes which take place in the separate constituents of the blood, I now proceed to notice some of the more important diseases in which those changes have been observed to occur.
usual appearances of blood in inflammatory diseases have already been described in treating of the buffed coat. The crassamentum is commonly supposed to be increased in bulk, but this is somewhat doubtful; and indeed it so much depends upon extraneous circumstances, such as the form of the vessel in which the blood is received, the time allowed for the contraction of the clot, which it is well known goes on for many hours, and even the quantity abstracted, that no accu rate deduction can be drawn from its appear ance. The collection of the fibrine itself is easily effected, and it will thus be perceived that, under inflammation, it is more abundant than in the normal state. Scudamore has made numerous experiments on the relative quantity of fibrine contained in healthy and diseased cras samentum, and the following short. list selected from them satisfactorily establishes this fact.
In 1000 grs. of clot as deduced from eight specimens of healthy blood, average of dry fibrine 3.53 grs.
Maximum 4.43, minimum Slight pleurisy, blood slightly buffed 7.05 Pain in the side, ditto 11.37 Cough .... .. 7.24 Acute gout, blood not buffed, firm texture 5.88 Disease not named, clot compact, buffed, and cupped 12.41 Ditto 13.73 Average .. 9.62 Mr. Jennings, in his report on the blood in the Transactions of the Provincial Medical sociation for 1834, likewise gives a table, the result of which is, that in eight cases of in flanarriation, the proportion of fibrine in the blood was increased from 2.1, which is Le canu's standard of health, to 9, 8, 11, 6, 5.3, 7, 6.9, 7 ; average 7.525, and that the alkaline salts were diminished from 8.37, the healthy standard, to 4.9, 4.8, 5.1, 4.3, 4.2, 4.4, 4, 5-6 ; average 4.61.