was necessary so to state the question. To explain: in the actual state of our knowledge we are only able to make two hypotheses relative to the cause of that vermilion coloring of the blood which flows from the gland when in function, with an activity so great that, as we have said, it is affected with pulsations like the arterial current when the secretion is very intense. We may suppose that the red venous blood is simply arterial blood which has passed the capillaries so rapidly as not to have had time to become properly venous, that is to say, to give off its oxygen so as to receive carbonic acid in its place. Or we may just as well admit that the red venous blood is ordinary venous blood, with this difference, that it is venous blood which does not continue black, because, having become venous at the moment of secretion, it disposed of its carbonic acid by the glandular excretion, which otherwise would have rendered it black, as happens when the gland is not secreting, and the carbonic acid cannot escape. This latter opinion acquires a great degree of probability, from the fact that all the liquid secretions furnish a large quantity of carbonic acid, either in solution or in a state of chemical combination. The comparative quantity of oxygen contained in the blood at its entrance into a gland and at its departure from the same organ is alone competent to determine the adoption of the one or the other of these two hypotheses. If, in proceeding from the gland, the red venous blood contains more oxygen than the black venous blood, and as much as the arterial blood, it is plain that it has never become venous at all. If, on the contrary, the red venous blood contains less oxygen than the arterial, and that in the same proportion as that which distinguishes the black venous blood, we must accept the second opinion, so as to infer that during secretion the arterial blood becomes venous as usual, with this peculiarity, that it remains red, because it disburdens itself of its carbonic acid on the spot, instead of waiting to eliminate it by the slower process of pulmonary exhalation. These, then, are the terms of the problem which I propose to solve: let us understand exactly what the experiment is competent to prove to us. I have operated on the blood of the renal vein because the volume of the organ permits us to obtain with ease quantities of blood sufficient for comparative analysis. In a vigorous dog, during digestion, after having, with proper precautions, exposed the renal vessels of the left side, I rapidly drew off* fifteen * This rapid drawing off of venous blood from the renal vein is somewhat difficult to effect. It is necessary to avoid tying the vein, since the blood then comes forth black on account of the obstacle to the circulation. For this reason I prefer to penetrate from the right through the vena cava, and plunge the canula of the syringe just into the left renal vein, in which the circulation will not then be interrupted. cubic centimetres of blood from the renal vein, and immediately brought it in contact with twenty-five cubic centimetres of carbonic oxide. This was done while urine was passing off abundantly by the ureter, and the venous blood was almost as bright a red as the arterial. Immediately afterwards one of the numerous branches of the renal artery was divided just at its entrance into the kidney, and from its cardiac section I drew off fifteen cubic centimetres of blood, which I likewise placed in contact with a like quantity of carbonic oxide. Then, in order to interrupt the urinary secretion, I removed the fatty envelope of the kidney. A few seconds afterwards the urine ceased to flow from the ureter, and the blood of the vein came forth black, like the venous blood of the vena cava. At that moment I drew off fifteen cubic centimetres of black venous blood from the kidney, which was, like the two others, placed in contact with twenty-five centimetres of carbonic oxide. After keeping it an hour apart, in a stove, at a temperature of from thirty to forty degrees, the analysis of the gas in contact with the three different kinds of blood, as above described, gave the following results as regards the quantities of oxygen which they contained, calculated for one hundred volumes of blood: For the red venous blood......... Volumes of Oxygen. 17.26 19.46 6.40 In a second experiment, the red venous blood was drawn as before from the renal vein during secretion, the arterial blood from the aorta, and the The results in one hundred volumes venous blood from the vena cava. According to these experiments, then, we see that the red venous blood. from the kidney (and it is presumable that the same takes place in blood from other glandular organs) differs from the ordinary venous blood, in the fact of not being as yet deoxidized. Thus we shall find our first hypothesis verified, so far as that blood has retained the characteristics of arterial blood. Nevertheless, though it is true for the proportions of oxygen found there, the absolute proposition cannot be considered exact. In fact, the red glandular venous blood contains much less fibrine than the arterial blood; it furnishes also less water, since it has supplied it for the secretion; and, moreover, this red venous blood shows itself more altera ble than the arterial: that is, it becomes black spontaneously much sooner when it has been separated from the vessels.* However that may be, limiting our researches, for the present, to the immediate object of our investigation, namely, the proportion of oxygen in the venous glandular blood, we observe this singular fact, that it is precisely during their function, that is to say, while they are secreting, that the glands suffer the blood to pass along red without deoxidizing it, and that while they are not in function, and are discharging no product, the blood which issues from them is black, deprived of much oxygen, and charged with carbonic acid.† * We remark these same properties in the venous blood from the head, when we have previously divided the great sympathetic in the middle region of the neck. The experiments which I have been making on this subject since 1852 have shown, that after the section of the sympathetic the circulation is considerably accelerated, the temperature augments, and the venous blood comes forth red, and the pressure augments. If, now, we galvanize the peripheral or superior extremity of the sympathetic, the circulation diminishes in intensity, the vessels contract, and the temperature diminishes, at the same time that the blood becomes very black. It is especially in horses that all these facts present themselves with the most decided evidence. The excessive instability in composition of this red venous blood demands that we bring it as quickly as possible in contact with the carbonic oxide, which prevents it from becoming venous, and from deoxidizing itself by the formation of carbonic acid. It is not my present intention to examine the question of the quantity of carbonic acid produced: I will only say, that with the carbonic oxide I have never found a quantity of carbonic acid corresponding to the quantity of oxygen which had disappeared; a fact which leads us to suspect that there must be something intermediate between the oxygen and carbonic acid. Here occurs to us anew that contrast between the glandular and muscular organs to which I have often before called your attention. The venous blood issues from the muscles all the more black and the more deoxidized, the more energetically the organ performs its function of contraction; from the glands the blood issues the more red and less deoxidized, the more the organ performs its function and secretes with intensity. But ought we to consider that opposition in the apparent phenomena as the proof of a radical difference in the processes of nutrition and secretion as they occur in the glands and muscles? In a word, are we able to say that while the muscles consume oxygen directly in virtue of their functional activity, the contrary is the case with the glands? or ought we not much rather, in the face of that singular result, to entertain doubts of the justice of our manner of designating the functional conditions of the glands? This, at least, is my opinion, and I think that these researches will lead us to interpret differently that which we call the state of repose and the state of function in the glands, and to distinguish there one state of chemical activity, and another of activity purely mechanical. I shall be able hereafter to allege various arguments in favor of this opinion, but I will end here with the very definite facts which I have thus far ascertained, confining myself to the mere statement of this obscure aspect of the question, which will serve as a point of departure for ulterior researches. [It will be seen that our author breaks ground for a new lecture on a profound and highly interesting topic, the rationale, that is, of the appaparent contrariety between the functional condition of muscles and glands. This is the very subject upon which we had prepared some remarks of our own; we wait, however, for the experiments of M. Bernard, which we trust to receive soon enough for our February number. Meantime, we present our readers with a cut copied from M. Bernard's Summer Course of 1856, representing his dissections of the submaxillary and sublingual glands of the dog, with the distribution of the two orders. of nerves whose antagonistic influence upon the processes of secretion and circulation in the glands is the subject of these experiments: A. The submaxillary gland. B. The sublingual gland. C. A tube introduced into the duct of Wharton. D. Another introduced in the duct of the sublingual gland. E. Superior cervical ganglion. LS. Lingual branch of the fifth nerve. F. Facial nerve. CT. Chorda Tympani. G. Submaxillary ganglion. H. Sympathetic nerve fibre proceeding along the carotid artery to the submaxillary gland. I. Internal maxillary artery. V. The Vidian nerve. K. Branches of the lingual nerve distributed to the buccal mucous membrane. The nervous branch, which comes off from G in a retrograde direction, to be distributed to the submaxillary, is the tympano-lingual nerve of Bernard it is well shown to be derived by the chorda tympani from the facial nerve, F; though in the submaxillary ganglion, G, reflex influence is doubtless received from the lingual branch of the fifth LS. It is under the influence of this nerve-twig that the gland secretes, and the venous blood from it is red, while under that of the branch H, from the superior cervical ganglion, the secretion and circulation are arrested, and venous blood is black. D. F. W.] |