Monthly retrospect of the medical sciences : January to December 1849 / edited by George E. Day, Alexander Fleming, W.T. Gairdner.

Date:
MDCCCXLIX [1849]
Catalogue details

Licence: Public Domain Mark

Credit: Monthly retrospect of the medical sciences : January to December 1849 / edited by George E. Day, Alexander Fleming, W.T. Gairdner. Source: Wellcome Collection.

    5/262 (page 3)
    the motion imparted by the heart’s systole to the surrounding elastic tissues. 5. Morbid conditions of the muscular structure of the heart, can have no effect in preventing closure of the valves. 6. As the small specific gravity of the valves is assumed to facilitate their closure, any thing which can render them specific¬ ally heavier, as fibrinous deposits, in the case of debilitated individuals whose blood is of low specific gravity, may be conjec¬ tured to interfere with their action. It is in such cases that the re-establishment of an improved condition of the blood re¬ moves the murmur, as in typhus fever, severe pneumonia,&c. On similar principles, the author adds, the bruits observed in chlorotic patients, may perhaps be ex¬ plained.—Prager Viertel-jahrschrift, 1847, vol. xi. [We witnessed the experiments referred to in this paper, when performed by Dr Hamernik, and have much pleasure in testifying to their accuracy. The experi¬ ment, by which it is shown that the auri- culo-ventricular valve is closed before, and independently of the ventricular systole, is very easy of performance. The valves, when cut out of the heart, are found to float readily on the surface of blood; and probably their specific light¬ ness plays a part in the mechanism of their closure, at least in the human subject; at the same time, that it is far from being essential is indicated in prone animals, and in the case of a man standing on his head. The seat of chlorotic murmurs pre¬ vents our attributing them to the cause hinted at by the author.] 2.—On the Changes which take place in the Lungs after Division of the Pneumo- gastric Nerves. By Dr Schiff.—It is well known that after section of the vagus nerves in the neck of an animal, death frequently takes place at an interval of a few days. In these cases the lungs are found to have undergone alterations, cha¬ racterised by congestion, and the elfu- sion of a large quantity of frothy sanguino- lent serum into the bronchi ; which le¬ sions have been ascribed by authors to the paralysis of the glottis consequent on the section of its nerve (the recurrent), which induces respiratory obstruction, ei¬ ther directly, or by permitting of the passage of food and other matters into the trachea. Dr Schiff has performed a variety of experiments which disprove these ideas. By cutting in some animals the recurrents, and in others the pulmo¬ nary branches of the vagus, he has con¬ vinced himself that the section of the lat¬ ter causes congestion, with tumefaction of the bronchial mucous membrane; while that of the former only produces narrow¬ ing and paralysis of the glottis, without any pulmonary changes. The lesions of the lungs are likewise unaffected by the performance of tracheotomy, and by the section of the oesophagus in the neck (in dogs). He therefore concludes, that the state of the lungs is dependent on the in¬ tegrity of the pulmonary portion only of the nerve. Section of the nerve on one side produced a slighter amount of pulmo¬ nary lesion, but never confined to the lung of one side ; a circumstance which M. Schiff accounts for by considering the anastomoses in the pulmonary plexus of nerves.—Archiv fur Physiologische Heil- kunde, 1847 ; Gazette M^dieale, 2d Dec. 1848. [Dr J. Reid considers the congestion and bronchial effusion as a secondary ef¬ fect of the diminished frequency of respi¬ ration in animals in which the vagi are divided.—(Ed. Med. and Surg. Journal, April 1839.) This idea agrees perfectly with the results of the above experiments; and is, we doubt not, quite correct.] 3.— On the Chemical Changes of Respi¬ ration. By MM. Regnault and Rbiset.— A new and very extended series of experi¬ ments on this subject have been instituted by MM. Regnault and Reiset, who give minute details of the several steps of the process employed by them, the precau¬ tions taken, and the kind of apparatus used. Their investigations, which are still in progress, seemed to be performed with much care and exactness, and their results may probably be fully relied on. The most important of these results is, that nitrogen is invariably exhaled through the lungs, though the quantity is small, rarely exceeding xotj^h of amount of oxygen consumed. Hydrogen, and certain carburetted gases, usnally present themselves in small quantity. As an illustration of the changes which Reg¬ nault and Reiset found to occur in the respired air, the following results of an experiment, in which a young dog was confined in the apparatus for twenty four hours and a half, may be quoted :— Grammes. Oxygen consumed - - - - 182-288 Carbonic acid produced - - 185-961 Oxygen contained in the car¬ bonic acid ------ 135-244 Nitrogen disengaged - - - 0-1820 If the quantity of oxygen consumed be represented at 100, then the results may be thus stated:—