scholarly journals V. A letter on a canal in the medulla spinalis of some quadrupeds

1809 ◽  
Vol 99 ◽  
pp. 146-147
Keyword(s):  
Royal Society ◽  
Human Subject ◽  
Cauda Equina ◽  
The Other ◽  
Small Stream ◽  
Spinal Marrow ◽  
The Brain ◽  
Contrary Direction

Sir, According to your request, I send you an account of the facts I have ascertained, respecting a canal I discovered in the year 1803, in the medulla spinalis of the horse, bullock, sheep, hog, and dog; and should it appear to you deserving of being laid before the Royal Society, I shall feel myself particularly obliged, by having so great an honour conferred upon me. Upon tracing the sixth ventricle of the brain, which corresponds to the fourth in the human subject, to its apparent termination, the calamus scriptorius, I perceived the appearance of a canal, continuing by a direct course into the centre of the spinal marrow. To ascertain with accuracy whether such structure existed throughout its whole length, I made sections of the spinal marrow at different distances from the brain, and found that each divided portion exhibited an orifice with a diameter sufficient to admit a large sized pin; from which a small quantity of transparent colourless fluid issued, like that contained in the ventricles of the brain. The canal is lined by a membrane resembling the tunica arachnoidea, and is situated above the fissure of the medulla, being separated by a medullary layer: it is most easily distinguished where the large nerves are given off in the bend of the neck and sacrum, imperceptibly terminating in the cauda equina. Having satisfactorily ascertained its existence through the whole length of the spinal marrow, my next object was to discover whether it was a continued tube from one extremity to the other: this was most decidedly proved, by dividing the spinal marrow through the middle, and pouring mercury into the orifice where the canal was cut across, it passed in a small stream, with equal facility towards the brain (into which it entered), or in a contrary direction to where the spinal marrow terminates.

scholarly journals A letter on a canal in the medulla spinalis of some quadrupeds. In a letter from Mr. William Sewell, to Everard Home, Esq. F. R. S

1832 ◽  
Vol 1 ◽  
pp. 325-325
Keyword(s):  
Fourth Ventricle ◽  
Human Subject ◽  
Transverse Section ◽  
The Other ◽  
Small Stream ◽  
Spinal Marrow ◽  
The Subject ◽  
Present Description ◽  
The Brain

The canal, which is the subject of this letter, appears to have been discovered by the author in the year 1803, although no account has been given of it till the present description was drawn up at the request of Mr. Home. From the extremity of the sixth ventricle of the brain in the horse, bullock, sheep, hog, and dog (which corresponds to the fourth ventricle in the human subject), a canal passes in a direct course to the centre of the spinal marrow, and may be discovered in its course by a transverse section of the spinal marrow in any part of its length, having a diameter sufficient to admit a large-sized pin; and it is proved to be a continued tube, from one extremity to the other, by the passage of quicksilver in a small stream in either direction through it.

scholarly journals II. The Croonian Lecture, on some physiological researches, respecting the influence of the brain on the action of the heart, and on the generation of animal heat

1811 ◽  
Vol 101 ◽  
pp. 36-48 ◽  
Keyword(s):  
Blood Vessels ◽  
Royal Society ◽  
Spinal Marrow ◽  
Animal Body ◽  
The Brain

Having had the honour of being appointed, by the President of the Royal Society, to give the Croonian Lecture, I trust that the following facts and observations will be considered as tend­ing sufficiently to promote the objects, for which the Lecture was instituted. They appear to throw some light on the mode, in which the influence of the brain is necessary to the conti­nuance of the action of the heart; and on the effect, which the changes produced on the blood in respiration have on the heat of the animal body. In making experiments on animals to ascertain how far the influence of the brain is necessary to the action of the heart, I found that when an animal was pithed by dividing the spinal marrow in the upper part of the neck, respiration was immediately destroyed, but the heart still continued to contract cir­culating dark-coloured blood, and that in some instances from ten to fifteen minutes elapsed before its action had entirely ceased. I further found that when the head was removed, the divided blood vessels being secured by a ligature, the circulation still continued, apparently unaffected by the entire separation of the brain. These experiments confirmed the observations of Mr. Cruikshank and M. Bichat, that the brain is not directly necessary to the action of the heart, and that when the functions of the brain are destroyed, the circu­lation ceases only in consequence of the suspension of respira­tion. This led me to conclude, that, if respiration was produced artificially, the heart would continue to contract for a still longer period of time after the removal of the brain. The truth of this conclusion was ascertained by the following experiment.

scholarly journals On the decussation of fibres at the junction of the medulla spinalis with the medulla oblongata

1843 ◽  
Vol 4 ◽  
pp. 71-72
Keyword(s):  
Medulla Oblongata ◽  
Royal Society ◽  
The Body ◽  
Cerebral Lesion ◽  
Common Occurrence ◽  
Satisfactory Explanation ◽  
Actual Structure ◽  
Spinal Marrow ◽  
Motor Columns ◽  
The Brain

The author first alludes to what usually happens in affections of the brain, namely, that the loss of voluntary power and of sensation, manifest themselves in the opposite side of the body to that in which the cerebral lesion exists, a fact which has been attempted to be explained by the crossing of the fibres at the junction of the medulla oblongata with the anterior or motor columns of the medulla spinalis ; but such a structure, he observes, affords no explanation of the loss of sensation. The author then, referring to the communication of Sir Charles Bell to the Royal Society, in the year 1835, describing a decussation connected with the posterior columns, or columns of sensation, mentions that the accuracy of these dissections was doubted by Mr. Mayo and other eminent anatomists. The author proceeds to state that the symptoms of cerebral lesion do not always take place on the opposite side of the body to that in which the lesion of the brain exists, but that they occur sometimes on the same side; that the loss of power and of sensation, although confined to the same side, may exist in either the upper or the lower extremity; but that both are not necessarily implicated; and that, in fact, cases occur where there are marked deviations from what may be considered the more common occurrence. Having observed such cases, and not being aware of any satisfactory explanation, the author examined with care the continuation upwards of the anterior and posterior columns of the spinal marrow into the medulla oblongata and found that the decussation at the upper part of the spinal marrow belonged in part to the columns for motion, and in part to the columns for sensation; and farther, that the decussation is only partial with respect to either of these columns; thus elucidating hy the observation of the actual structure what before appeared very unsatisfactory in pathology, and anomalous in disease. The paper is illustrated by drawings made from the dissections of the author.

scholarly journals XIV.—Of the Fourth and Sixth Nerves of the Brain;—being the concluding paper on the distinctions of the Nerves of the Encephalon and Spinal Marrow

1839 ◽  
Vol 14 (1) ◽  
pp. 237-241 ◽  
Author(s):  
Charles Bell
Keyword(s):  
Optic Nerve ◽  
Royal Society ◽  
Circular Muscle ◽  
Complex Nature ◽  
Spinal Marrow ◽  
The Subject ◽  
The Brain ◽  
Royal Society Of London

Interesting as theoptical properties of the eye have been to philosophers in every age, there are conditions of this organ which are no less curious, and which have not had their share of attention.In the year 1823, I introduced the subject to the Royal Society of London, nearly in the terms I am now using, but there is much more in the subject than I then conceived, although I see no reason to change the mode of contemplating it.The eight muscles of the eye, and the five nerves, exclusive of the optic nerve, which pass to them, imply the complex nature of the apparatus exterior to the globe, and I fear it is too plain that the subject has not been satisfactorily treated.It is chiefly with respect to the protecting motions of the eye that the difficulty occurs, for I hope the dependence of the proper organ of vision on the voluntary muscles of the eye, has been proved and acknowledged.Permit me to draw the attention of the Society to what appears a very simple piece of anatomy, the circular muscle which closes the eyelids, orbicularis palpebrarum.

Continuation of the paper on the relations between the nerves of motion and of sensation, and the brain; and more particularly on the structure of the medulla oblongata and of the spinal marrow

1837 ◽  
Vol 3 ◽  
pp. 331-332
Keyword(s):  
Spinal Cord ◽  
Medulla Oblongata ◽  
Fourth Ventricle ◽  
Cauda Equina ◽  
Spinal Marrow ◽  
Spinal Nerves ◽  
Auditory Nerves ◽  
The Right ◽  
The Brain ◽  
External Coating

The author enters into a minute anatomical investigation of the structure of the spinal cord, and of its relations with the encephalon, and with the origins of the nerves. He finds that the spinal cord is constituted, in its whole length, by six pairs of columns, namely, two posterior, two lateral, and two anterior; each column being composed of concentric layers, and invested with an external coating of cineritious substance, and all the columns being divided from each other by deep sulci, which penetrate nearly to the centre of the cord. On tracing the posterior columns in their ascent towards the encephalon, they are seen to diverge laterally at the calamus scriptorius , or bottom of the fourth ventricle, and to proceed into the substance of the cerebellum. Each of these posterior columns is here found to consist of two portions, the outermost being the largest; and they now constitute the processus cerebelli ad medu oblongatam . This subdivision of the posterior columns may be traced throughout the whole length of the spinal cord. The lateral columns give origin to the posterior roots of the spinal nerves, and are therefore the parts subservient to sensation. In ascending towards the brain, each of these columns has a double termination; first, in the root of the fifth pair of cephalic nerves; and secondly, in the place where both columns unite into one round cord, and mutually decussate. Between the lateral and the anterior columns there is interposed a layer of cineritious matter, constituting a continuous stratum from the cauda equina to the roots of the auditory nerves. There is also a septum, dividing the right and left tracts subservient to sensation in the region of the fourth ventricle, and apparently terminating at the point of decussation of these tracts; but, in reality, separating to allow of this decussation, and joining the central portion of the cord, which connects the posterior with the anterior columns, and extends from the pons Varolii to the cauda equina .

scholarly journals XXII. On the respiration of birds

1829 ◽  
Vol 119 ◽  
pp. 279-286 ◽  
Keyword(s):  
Guinea Pig ◽  
Royal Society ◽  
Human Subject ◽  
The Other ◽  
Pure Oxygen ◽  
Atmospheric Air ◽  
Glass Vessel ◽  
The Subject

Our communications to the Royal Society, as printed in the Phil, Trans. for 1808 and 1809, detailed the effects produced when the human subject or a guinea-pig respired, either atmospheric air alone, or pure oxygen, or a mixture of hydrogen and oxygen. We thought it would render the subject more com­plete if we extended our inquiries to the respiration of birds, and accordingly made several experiments with pigeons in the same apparatus that we employed for the guinea-pig. The apparatus is engraved and described in the Phil. Trans. for 1809, page 429. First experiment with atmospheric air. A pigeon was placed in the intermediate glass vessel, in 62 inches of air on the mahogany stand over quicksilver, between the two gasometers communi­cating with the vessel in which the pigeon was confined. One of the gaso­meters was empty, but connected by tubes and stop cocks with the quicksilver bath, and also with the intermediate vessel; the other contained the air for the supply of the pigeon. The barom. being 30.130, the therm. 54°, during 69 mi­nutes, at intervals of four or five minutes, 35 cubic inches at a time of com­mon air were slowly passed through the vessel in which the bird was con­fined; the other gasometer of course received what was pushed off, the quan­tity was noticed by its register, and a portion was received by a bottle in the quicksilver bath for examination; in this way 525 cubic inches of common air were supplied, to which the 62 cubic inches in the intermediate glass vessel being added, made a total of 587 cubic inches in which the pigeon had respired for 69 minutes. The registers of both gasometers agreed throughout to a very trifle, which confirmed our former observations, that there is no change in the volume of atmospheric air when respired under natural circumstances.

scholarly journals On the relation which subsists between the nervous and muscular systems in the more perfect animals, and the nature of the influence by which it is maintained

1837 ◽  
Vol 3 ◽  
pp. 164-165
Keyword(s):  
Nervous System ◽  
Royal Society ◽  
Spinal Marrow ◽  
Chemical Agents ◽  
The Subject ◽  
The Brain ◽  
Mechanical Irritation ◽  
Nervous Influence

The author, after referring to his former papers which have at different times been read to the Royal Society, and published in their Transactions, is led to view the brain and spinal marrow as the only active parts of the nervous system 3 the nerves, whether belonging to the class of cerebral or ganglionic, together with their plexuses and ganglions, serving only as the means of conveying and combining the various parts of the former organs, and therefore being passive with reference to their functions. This view of the subject is directly opposed to that which has been adopted by many physiologists, who consider these ganglions as the sources, and not the mere vehicles, of nervous influence. In order to determine this point, the author made the following experiment on an animal that had been pithed so as to destroy its sensibility, while the action of the heart continued. Under these circumstances, he applied mechanical irritation, and also various chemical agents, to the ganglions and plexuses of the ganglionic nerves, and found that the heart continued to beat with the same regularity as before, and with the same frequency of pulsation.

VI. Experiments made with a view to ascertain the principle on which the action of the heart depends, and the relation which subsists between that organ and the nervous system

1815 ◽  
Vol 105 ◽  
pp. 65-90 ◽  
Keyword(s):  
Nervous System ◽  
The Body ◽  
The Other ◽  
Modus Operandi ◽  
Spinal Marrow ◽  
Difference Of Opinion ◽  
The Subject ◽  
The Brain ◽  
General Opinion ◽  
Nervous Influence

The following experiments were begun with a view to as­ certain the manner in which certain poisons act in destroying life. I soon found that, in order to make any considerable progress in such an inquiry, it is necessary to ascertain how far the powers of the nervous and sanguiferous systems di­rectly depend on each other. There seems never to have been any difference of opinion respecting the direct depend­ence of the nervous on the sanguiferous system. When the powers of circulation are increased or diminished, the nervous system always suffers a corresponding change, nor can the latter, under any circumstances, continue to perform its functions after the former are destroyed. I speak of the warm blooded animals. In cold blooded animals the process of dying is so slow, that the functions of the nervous system abate very gradually, after the circulation has wholly ceased. The converse of the above proposition is by no means so generally admitted. It is evident that certain changes of the nervous, produce corresponding changes in the sanguiferous, system ; yet, while some assert, that the action of the heart depends as immediately on the brain, as that of the latter does on the heart, others maintain, that the nervous power may be wholly destroyed without impairing the vigour of this organ. This point it is necessary to determine, before we can trace with precision the modus operandi of poisons. The following inquiry therefore may be divided into two parts. In the first, I shall endeavour to ascertain how far the power of the heart is influenced by the state of the nervous system; in the other, by what steps certain poisons destroy the powers of both. This I shall reserve for another paper, and here confine my­self to the first part of the subject. Till the time of Haller, it seems to have been the general opinion, that the muscles derive their power from the nervous system. He taught, that the power of the muscles depends on their mechanism, that the nervous influence is merely a stimulus which calls it into action, and consequently that those muscles, the heart for example, which act only by the appli­cation of one peculiar stimulus, unconnected with the nervous system, are wholly independent of it. This opinion seemed confirmed by its being generally admitted, that the action of the heart continues after it is removed from the body, and that it cannot be influenced by stimulating the brain, or spinal marrow, or the nerves which terminate in it. Haller and his followers maintain, that there are two distinct vital powers, one of the nervous and another of the sanguiferous system.

scholarly journals On the refraction and dispersion of krypton and xenon and their relation to those of helium and argon

1908 ◽  
Vol 81 (549) ◽  
pp. 440-448 ◽  
Keyword(s):  
Royal Society ◽  
Wave Length ◽  
Chemical Society ◽  
The Other ◽  
Refractive Indices ◽  
Mercury Lamp ◽  
Bright Band ◽  
Point Of Departure ◽  
Micrometer Eyepiece ◽  
Contrary Direction

By the kindness of Sir William Ramsay and Prof. R. B. Moore, we have been enabled to measure the refractive indices of krypton and xenon with much larger quantities of these gases than were available at the time of their first isolation. The method of preparation of the gases will be given by Prof. Moore in a paper about to be presented to the Chemical Society. The procedure followed in determining the indices is described in a paper lately published by the Royal Society, and need be only briefly recapitulated. Jamin’s refractometer was used, and the source of light was, for the refraction, a Bastian mercury lamp, and for the dispersion, a Nernst lamp in conjunction with a fixed-deviation spectroscope. In measuring the dispersion, one of the two tubes was filled with the gas in question, and the other with air at such a pressure that the optical lengths of path of the two interfering rays were approximately equal. The light was then continuously changed from λ = 6500 to λ = 5000, and the change in the position of the centre of a given bright band was observed in a telescope fitted with a micrometer eyepiece. The distance on the same scale between the centres of two adjacent bright bands of known wave-length (generally λ = 5461) was also noted. These observations constituted the point of departure. The pressure of the gas in one tube was then altered till a convenient number of bands of wavelength 6500 (usually 85) had passed in one direction; and, next, the pressure of air in the other tube was altered till the same number of bands had passed in the contrary direction. The wave-length of the light was then changed from the first wave-length to the second, and the movement of the centre of the bright band under observation was again noted.

scholarly journals XXIV. Some additional experiments and observations on the relation which subsists between the nervous and sanguiferous systems

1815 ◽  
Vol 105 ◽  
pp. 424-446 ◽  
Keyword(s):  
Royal Society ◽  
Spinal Marrow ◽  
Femoral Arteries ◽  
Cold Blood ◽  
Voluntary Motion ◽  
The Brain ◽  
The Web ◽  
Made In

In a paper which I had the honour to lay before the Royal Society, I observed that M. le Gallois founds his explanation of many of the phenomena which he describes in his Treatise, Sur la Principe de la Vie , &c. on the supposition that the circulation nearly ceases in any part when that portion of the spinal marrow from which it receives its nerves is destroyed. The accuracy of this supposition many circumstances led me to question. It is easy to subject it to the test of experiment. Exp . 1. The spinal marrow of a frog was destroyed by moving, in various directions, a wire introduced into the spine by a hole made in the lowest part of it, and passed up into the brain. The animal was immediately deprived of sensibility and voluntary motion, and appeared to be quite dead. After it had lain in this state for several minutes, part of the web of one of the hind legs being brought into the field of a microscope, the blood was seen circulating in it as rapidly as in the web of a healthy frog. In making such experiments it is necessary to be aware, that handling and stretching the web tends to impair the vigour of the circulation in it. If this experiment is objected to on account of its being made on an animal of cold blood, I may refer to the seventh and eighth experiments related in the paper above alluded to, in which the carotid and femoral arteries were found beating and performing the circulation after the spinal marrow had been wholly destroyed.

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