1847] Effects of Bleeding upon the Mass of the Blood. 319 it, a second degree of intensity; and still other points, which however are for the most part very limited, in which the process goes on with its highest intensity. In such a case the blood will furnish a very consistent coagulum, and one rich in fibrine, which will cover it with a thick coriaceous buff, and upon the surface of this gelatiniform deposits will be observed." P. 371. The reasons which have induced the author to consider the parafibrine or gelatiniform crust to denote the highest intensity of the inflammatory process are the following. 1. It appears much more frequently in the earlier than in the later periods of the disease, when all the symptoms denote the activity of the process; and disappears before the bradifibrine (or coriaceous crust), and long before the simply increased fibrine (firm coagulum) as the disease advances towards its cure. 2. It appears as a consequence of intense inflammation of the skin excited by blisters, &c., but not when this exists in a milder degree. 3. It is found in the fluids produced in various intense inflammations, such as pleurisy, &c. In a note the author states, that Dr. Gamberini, one of the most careful observers in Italy, has informed him that he hardly recollects a case in which the appearance of gelatiniform flakes and lines upon the clot was not accompanied with great intensity of the disease. SERIES IV.-ON THE EFFECTS OF THE ABSTRACTION OF BLOOD "If the abstraction of blood were confined to the production of a greater or less diminution of this fluid, and to a proportionate decrease in the vital power and in the functions of the part which most nearly depend upon it, the question of bloodletting would be one of such simplicity that its mere proposition would suffice for its solution. But the effect of bleeding cannot be regarded as a direct diminution of vital power solely because it induces a direct diminution of the material for the exercise of life; nor as an enfeeblement of that power because it directly lessens a means necessary for its manifestation. It may and does produce these effects, not however in a direct way, but by a series of successive and reciprocal modifications, that furnish an explanation of all the various phenomena, to which the loss of blood, whether in the physiological or morbid condition, gives rise to. "The first modification which the abstraction of blood induces in the organism is exerted upon the blood itself; a modification both immediate and great, though hitherto not noticed, or only superficially so, by clinical observers. And it is from this modification that all the other multiplied phenomena originate. It is from having commenced the examination of the different effects of bloodletting in an inverse order-from having sought for the material and functional changes in the solids consequent upon it, before examining what changes the circulating residuum itself had undergone that the study of this subject has proved arduous, vague, and, I may add, of little utility. I have no intention to attempt the examination of the intimate dynamic or molecular changes which the blood under this influence undergoes, because I do not feel certain of the utility of inquiries during which the senses do not continuously bear us company; nor have I the intention of submitting the blood to chemical decomposition and the forced isolation of its principles by means of re-agents and analyses, because the indications derivable from these do not seem to me all equally to be relied upon. But I believe that the mere accurate determination of the principal sensible phenomena which the blood under such circumstances presents, may be so conducted as to Z * produce an assemblage of precise expressions of its manner of modifying itself in strict relation with its material conditions, and the amount of vitality it indicates. And it is the result of the study of such modifications which I am about briefly to advert to, with above all the intention of showing the extent to which we may determine with exactitude the influence of bloodletting on the cure of diseases; and of what importance the determination of this is in clinical practice."-Vol. 121, p. 7. The mass of the blood may be modified after venesection as respects its quantity, its quality, and its motion. 1. Effects of Bloodletting upon the Quantity of the Blood.—It is an error to suppose that the mass of the blood becomes diminished in quantity in proportion to the amount abstracted. To prove this, it is only necessary to examine, by means of the areometer, portions taken at the commencement and at the conclusion of a venesection, when the latter will be almost invariably found to be of less density than the former. M. Polli has supplied several tables deduced from often-repeated investigations of the exact amount of this diminution of density, both during any one bleeding, or from one bleeding to another, when these have been repeated. The following are the conclusions at which he arrives. "1. The blood which at the end of the emission possesses a less density than that first drawn, and its serum which is often found to be of greater density than that which accompanies the first blood (though of lesser than the whole mass of the blood), prove that, during the very act of bleeding, there is absorbed into the circulating channels a greater or less quantity of serum of varying density. 2. The quantity of serum that enters the circulation during an ordinary bloodletting, to induce in the totality of the remaining mass the mean dilution which the areometer exhibits, is approximatively equivalent to a thirtieth part by weight of the remaining blood. 3. The quantity of serum which is absorbed from one bleeding to another in an interval of twelve hours, is about double that amount. 4. The dilution of the blood which takes place during bleeding is principally produced by the mechanical forcing into the vessels, by means of atmospheric pressure, of the fluids which everywhere moisten the tissues; but the dilution which takes place from one bleeding to another, is the effect of an absorption governed by the vital laws." P. 27. There are certain facts, also, which are explained by the above circumstances, such as the thirst which patients so often experience after bleeding; the dryness of the mouth and fauces, which women suffering from great metrorrhagia complain of; the diminution or even complete absorption of some dropsies after free bleeding, &c. "As regards the question before us, the human body may be regarded as a spongy tissue, entirely permeable by the different humours which fill its cells and freely traverse its vessels. The atmospheric pressure to which it is submitted not allowing that any cell or any vessel shall remain empty or only partially filled, is continually propelling the liquids to whence least resistance offers itself, cooperating with the vital action of the tissues and the fibres which constantly contract on the volume of the contained fluids. During the aspiration which is immediately produced by opening a vein, the liquids which proceed constantly to dilute the mass of the blood may be regarded then as only mechanically driven into the vessels, and they do not in fact exceed in quantity the amount of blood lost; but, in the intervals which occur between one bloodletting and another, the diluting liquids are physiologically introduced by means of the absorbents, when 1847] Modifications of the Blood by Bleeding. 321 too they are more elaborated, and often temporarily in greater quantity than suffices to replace the blood taken. And this explanation leads to the establishment of the difference which exists between a free evacuation of blood at one time, and a number of smaller abstractions made at different periods, although, taken altogether, not more blood is taken by the one plan than by the other." P. 23. Practical Applications.-The fact of the rapid absorption of fluids which supervenes on venesection may be advantageously borne in mind when we have in view the augmentation of the operation of certain medicinal substances, the diminution of the density of the blood, and the removal of effusions from important organs; while, when we wish to delay absorption in the case of poisoning, purulent infection, &c., we must abstain from the abstraction of blood. Employed during the existence of an abscess, and especially if this is in communication with the air, it would become but the means of inducing a more general poisoning of the blood. So, just as the operation of purgatives and emetics long taken without any effect being produced is thus much expedited; and a prudent emission of blood will favour the specific action of mercury; so in recent poisoning, and in those some what similar cases of gastric-bilious saburræ of an acrid and putrefective character, venesection but hastens the fatal result. "To the same cause, also, we may attribute the promptly fatal termination of certain chronic affections of spoiled organs, which nature had nevertheless endeavoured to maintain in an isolated condition, and which uncompromised by bleeding might not so readily have terminated life.” 2. Effects of Bloodletting upon the Qualities of the Blood.-The blood may be qualitatively modified in respect to its density, its coagulability, and its temperature. (A). Modifications of the Density of the Blood.-These have been already briefly alluded to in the foregoing section: but the author here enters into the subject in great detail, exhibiting the tabular results of observations he has made on patients, and of numerous experiments he has performed on the horse. The questions he announces for solution are-1. What are the laws which govern the diminution of the density of the blood in general, during the same bleeding, and in the intervals of different bleedings? 2. What are the laws which govern the recovery of its density by the blood, after the cessation of such evacuations ? 3. What is the relation which these modifications of the entire blood bear to those of its serum; and to what extent do they also take place in respect to its other component parts? To follow him through the detailed replies he furnishes, would far exceed our limits; but we may state, as the general result, that the density of the blood was found to diminish in proportion to the amount abstracted; and to be recovered after the abstraction had ceased, in proportion as the individual had become otherwise restored to his normal condition. Comparing the condition of the mass of the blood with that of its serum, "the blood loses nearly 2 of its cruor to one of the solid materials of the serum, as the effect of several bleedings; while, during the same bloodletting, the loss seems exclusively to affect the cruor, the serum almost always increasing in density." The relative condition of the various component parts of the blood is thus stated : "The speedy dilution of this fluid is far from merely consisting in a simple watery addition to its mass; and the term Hydræmia, proposed to distinguish this particular condition, would only express one of the modifications it undergoes, and that perhaps the least important. Recapitulating the variations which the blood presents in its principles, with a diminution of its density, and availing ourselves not only of our own areometrical data, but also of the analytical results declared by hæmatologists in recent times, we may conclude "1. That, as a consequence of a series of moderate bloodlettings practised at short intervals in the same individual, the fibrine is stationary; the red globules and albumen diminished; the saline, fatty, and extractive matters are rather stationary than in excess; and the water is increased. 2. That, at the conclusion of a single very free bloodletting, the fibrine is increased; the red globules are diminished; the albumen is stationary or increased; the saline, fatty, and extractive matters, and the water are increased. 3. That, as a more remote consequence of one very abundant blood-letting, the fibrine diminishes; the red globules continue to diminish; the albumen is diminished; the saline matters, extractive, fatty matters and water increase. "The materials most easily reproduced in the circulatory mass after abstraction are then the water, the saline and extractive matters, and the fibrine; the albu men is reproduced with more difficulty, but the red globules with much more so. One of the effects of bloodletting the least easy to remove is the defect of red globules; and as these are the most vital portion of the fluid, constituting almost organized beings functioning of themselves, we may say that blood-letting tends to deprive the blood of its most characteristic element: and this condition of the fluid will consequently be more faithfully expressed by the term despoliation (spogliazione), employed a century ago by Quesnay, than by the terms hydramia or anemia, used by the moderns. "By bleeding, then, the blood is despoiled of its most noble constituents, becomes watery, and is mixed with ill-elaborated materials, having little affinity with it. The vital excitement of the tissues and nerves is thus intercepted and depressed, just as it would be by a direct injection of foreign matters into the blood; so that, in this point of view, bloodletting is a species of poisoning of the blood itself, greater or less according to the quantity taken and the mode of its abstraction. And it is of this poisoning of the blood, as well as of the deprivation of its more perfect constituents, that medicine avails itself, when abstracting blood, to overcome or moderate processes of irritation or inflammation; it presents directly to the patient thus suffering, as succedaneous and adjuvatory to blood-letting, small doses of poison, which absorbed into the blood, reproduce in part the good effects directly derivable from blood-letting."—Vol. 121, p. 79, An increased quantity of fibrine after repeated bloodletting is not only found in man suffering under inflammation, and kept on low diet; but also in healthy horses kept also on short commons, and bled day by day. The evacuation of blood alone, then, leads to the production of fibrine as noticed already by Pessina and others. "In our experiments upon the horse we have stated that the thickness of the crust was proportioned to the frequency of the abstraction; so that when, after the first bleeding, it formed but a third or a fourth of the coagulum, after the last it constituted four-fifths. The principal cause of this increasing thickness of the crust is the diminished density of the blood and the paucity of red corpuscles, by reason of which these are enabled speedily to descend to the bottom 1847] Modifications of the Blood by Bleeding. 323 of the recipient, where they occupy a small space only, leaving a proportionally larger stratum to figure as a crust. This crust may be called the false buff or buffiness from bloodletting, to distinguish it from the phlogistic buffiness, which occurs in blood far denser and more rich in red globules, and whose principal cause is slowness of coagulation." P. 72. (B). Modifications of the Coagulability of the Blood.-This point has been too minutely considered in our abstract of the First Series of the author's Researches to require further notice here. We may merely observe that his experiments upon horses confirmed the conclusions he arrived at at the bed-side, and which he sums up in the following proposition. · In proportion to the quantity of blood taken at one bloodletting, the shortness of the interval which transpires between different bleedings, and to the number of these abstractions practised on the same individual, so much the more readily will the blood be found to coagulate, or so much the less resistance will it present to the coagulation of its fibrine." (c). Modification of the Temperature of the Blood.-The investigations of Nasse, Marshall Hall, and Popp, are adverted to in this section and from these, together with a numerous series of original observations, Dr. Polli arrives at the following conclusion: "That the immediate effect of bleeding is to diminish_the_temperature of the remaining blood, and of the subject to which it belongs; but that, some time after the bleeding, and upon the repetition of the bleeding in the same individual, an opposite effect, or an elevation of the temperature, is produced. "The causes, by reason of which among the effects consequent on bloodletting there is an elevation of temperature, are complex, and it must suffice here to indicate them. 1. The acceleration of the circulation, which renders the respiration also more frequent, and the pulmonary hæmatosis more active. 2. The introduction of combustible substances, especially fatty matters, by means of the more active absorption induced by the bloodletting, the which, when commingled with the inspired oxygen, must necessarily furnish new elements of calorification."-Vol. 121, p. 267. (D). Practical Applications.-(1) In the inflammatory diseases of the pulmonary organs, the blood can be held in an attenuated and diluted state under the influence of bloodletting to a far greater extent than by the imbibition of aqueous fluids; and in this way is expectoration rendered easier than it otherwise would be. (2) Profuse sweating, abundant alvine excretions, prolonged abstinence from drink, and whatever increases pulmonary exhalation (as exercise, a warm, dry, or rarified air), render the blood more dense; and hence some of the benefit which persons of lymphatic constitutions derive from a residence in mountainous regions, and the free use of purgatives. Becquerel has pointed out the fact of the frequent use of purgatives rendering the urine scarce and sedimentiferous: and, as a strict relation prevails between the density of the urine and that of the blood, care should be taken, in the case of pure plethora, not to aggravate, by the use of these substances, a condition of the blood which is only relievable by bloodletting. (3) It is not a matter of indifference whether a given amount of blood be abstracted at one bleeding or at several. By the first plan a much more complete and sudden modification of its mass is produced, and an effect |