721x 



PHYSIOLOGY OF THE NERVOUS SYSTEM. 



the spinal cord and to its intrac'ranial continu- 

 ation, which form a connection with the grey 



matter of the cord. Of these fibres some 

 are afferent or incident, others efferent or re- 



contractions of the larynx, but of which those of 

 the heart are entirely independent. The influence 

 of the stimulus upon the heart is immediate. That 

 of a stimulus applied to the larynx must pass to 

 the medulla oblongata, and be reflected upon the 

 part moved." 



The details of further experiments next follow. 

 The author refers to the reflex function the power 

 which the hedgehog has of assuming the form and 

 firmness of a ball.(?) Cases of infants born without 

 brain or cerebellum are referred to in proof of the 

 existence of reflex actions in the young of the hu- 

 man subject. The experiment of dividing the spinal 

 marrow between the nerves of the superior and 

 inferior extremities is described, to show '' two 

 modes of animal life ; the first being the assem- 

 blage of the voluntary and respiratory powers with 

 those of the reflex function and irritability; the 

 second, the two latter powers only ; " " if the spinal 

 marrow be now destroyed, the irritability alone 

 remains, all the other phenomena having ceased." 

 Dr. Hall next shows that the reflex function ad- 

 mits of exaltation and diminution. Frogs are made 

 tetanic by opium and strychnine, and the tetanus 

 disappears on removing the spinal marrow. On 

 the other hand, a few drops of hydrocyanic acid 

 placed upon the tongue of a frog depress the reflex 

 function ; " the contractions which depend on the 

 reflex function are observed to become less and less 

 energetic and excitable, and at length cease alto- 

 gether." 



Some highly interesting references are made to 

 the light thrown upon the nature of certain diseases 

 by our knowledge of this reflex function. The mor- 

 bid states produced by dentition, epilepsy, asth- 

 ma, tenesmus and strangury, tetanus and hydro- 

 phobia, are the principal diseases mentioned. 



The rest of the paper consists of inferences from 

 the preceding parts and a recapitulation. 



Dr. Hull had formed, at this time, no distinct 

 hypothesis respecting any special mechanism for the 

 reflex function. He makes the following remarks, 

 which seem to foreshadow his subsequent hypo- 

 thesis referred to in the text. " It appears pro- 

 bable," he says, " that the facts of this paper may- 

 lead to some important additions to our knowledge 

 of anatomy, by inducing an accurate inquiry into 

 the origin, course, connection, and distribution of 

 the subcutaneous, or submucous, and muscular 

 nerves, which constitute the arcs of the reflex 

 function." 



In reviewing this interesting and important paper, 

 it is impossible not to feel the greatest regret that its 

 author should have done so much injustice to him- 

 self as well as to those who had preceded him, by 

 neglecting to give an exact account of the state of 

 science in reference to this question at the time he 

 wrote. No one who peruses with candour the essay 

 of Prochaska can deny that it contains, with re- 

 gard to the reflex function, everything thatDr. Hall's 

 paper contains, everything which will bear the test 

 of careful analysis, omitting those views which are, 

 indeed, peculiar to Dr. Hall, and which do not 

 appear in this paper, assigning to the cord pow- 

 ers over ingestion, egestion, muscular tone, and 

 irritability, &c. Throughout the whole paper no 

 allusion whatever has been made to Prochaska's 

 essay. The Report of certain members of the In- 

 stitute upon the work of Le Gallois, (both of which 

 Dr. Hall quotes,) makes distinct reference to Pro- 

 chaska's views of the reflection of sensorial impres- 

 sions. It must not, however, be forgotten that 

 Prochaska's views had fallen into oblivion and 

 neglect, and that Dr. Hall revived them, illus- 

 trated them by experiments, and showed their ap- 

 plication to the pathology of the nervous sys- 

 tem. I may add, that nothing would be more 

 excusable than that a physician, working <U these 



subjects in 1832, should be ignorant of Prochaska's 

 essay published in 1784, more especially as it was 

 overlooked even by his own countrymen by such 

 men as Treviranus, Rudolphi, and Miiller. 



Dr. Hall's next publications, as he himself states, 

 (Preface to Memoirs on the Nervous System, 1837,) 

 were a course of lectures, delivered from a printed 

 syllabus in the summer, and repeated in the winter 

 of 1835, of which one was inserted in the Medical 

 Gazette for January, 1836, and the whole in his 

 Lectures on the Nervous System and its Diseases, 

 published in April, 1836. 



It is in this latter work that, so far as I have been 

 able to ascertain, Dr. Hall first put forward the hy- 

 pothesis detailed in the text. It is stated, however, 

 not as a hypothesis, but as a discovered fact. Having 

 described two divisions of the nervous system, the 

 first consisting of the cerebrum and cerebellum 

 with sentient nerves, which pursue their course to 

 them, and of motor nerves, which proceed from 

 them either along the base of the brain or along 

 the spinal marrow, and then along every external 

 part of the animal frame, and the second com- 

 prehending the sympathetic, Dr. Hall goes on to 

 say : " To these two subdivisions of the nervous 

 system, I believe a third must be added before our 

 views of that system can be considered as at all 

 complete ; it is one which I claim the merit of first 

 pointing out in all its fullness. Suppose the cere- 

 brum and cerebellum, the centre of the first sub- 

 division of the nervous system, and the ganglionic 

 or the second subdivision of this system removed, 

 this remains. It consists of the true spinal marrow, 

 distinguished from the sentient and motor nerves, 

 which run along its course as an axis of ejrcitor 

 and motor nerves. It is the seat of a peculiar 

 series of physiological phenomena, and of a pe- 

 culiar class of pathological affections." " In the 

 former are included all (sic) the functions which 

 relate to the immediate acts of ingestion and eyestion; 

 in the latter, all spasmodic diseases." (Loc. cit. 

 p. 11.) 



Further on, in the same work, Dr. Hall gives an 

 analysis of his true spinal or excito-motory sys- 

 tem, which consists, according to his description, 

 of, 1. the Membranes; 2. the True Medulla ; 3. 

 the True Spinal Nerves. The principal divisions 

 of the true medulla, he specifies as follows : 



1. The Tubercula Quadrigemina, 



2. The Medulla Oblongata, 



3. The Medulla Spinalis, and especially its 



1. Cervical, 



2. Dorsal, 



3. Lumbar, and 



4. Sacral portions.* 



The reader who has perused with attention the 

 analysis of Prochaska's work given in the text will 

 perceive a striking resemblance between this true 

 Medulla and the Sensffi'ium commune of Prochaska, 

 p. 721 E. 



In this work there is no allusion to the impor- 

 tant essay of Prochaska, although Sir Charlrs 

 Bell is corrected for attributing the discovery of the 

 ganglia on the posterior roots of the spinal nerves 

 and on the portio major of the fifth to Monro in- 

 stead of to Prochaska (p. 17), and two quotations 

 are made from the latter author without specifying 

 the work from which the passages are quoted. 



In 1837 Dr. Hall published a quarto volume, 

 with the title, " Memoirs on the Nervous System." 

 This consists of a reprint of the paper published 

 in the Philosophical Transactions, " On the Reflex 

 Function of the Medulla Oblongata and Medulla 

 Spinalis j" and also of a paper which was read 



* An anatomical oversight, as the medulla spi- 

 nalis has no sacral portion. 



