BROWN- SEQUARD ON THE CENTRAL NERYOU3 SYSTEM. 401 



that offered by Prochaska, yet we freely admit that he puts forward his 

 view remarkably clearly and well. Let him speak for himself : — 



" In the preceding Lecture (Lecture ix.) we have said that there are two modes 

 of action of the nervous system upon the production of the phenomena of nutrition 

 and secretion. By one of these actions the nervous system determines an increase 

 in the attraction of blood by the living tissues, and in this case the phenomena are 

 accompanied by a dilatation of the blood-vessels, while the reverse exists when the 

 nervous system, instead of acting upon the parenchyma of the tissues, acts upon the 

 walls of the blood-vessels, and produces a constriction. In the first case, the quan- 

 tity of blood passing through the part on which the nervous system has acted, is 

 increased, while in the second case it is diminished ; in the first case the secretions 

 are increased, in the second diminished. In the first case, nutrition is more active, 

 and there is a tendency to hypertrophy and an augmentation of the vital properties 

 of nerves and muscles ; in the second case, nutrition is not active, and there is a 

 tendency to atrophy, and a diminution of the vital properties of nerves and muscles; 

 lastly, in the first case, there is an augmentation of temperature, while in the second 

 there is diminution. There is therefore the most complete difference between these 

 two nervous influences. 



" Let us now employ the knowledge of these two modes of action of the nervous 

 system, to explain what occurs in some cases of secretory, or nutritive, reflex phe- 

 nomena. Suppose, for instance, a calculus in one of the ureters : it irritates the 

 centripetal nerve fibres of this canal, the irritation is transmitted to the spinal cord, 

 which reflects it upon the muscular coat of the blood-vessels of the two kidneys, and 

 produces a contraction, in consequence of which there is much less blood passing 

 through these organs, so that the urinary secretion is stopped or much diminished. 

 Suppose a worm in the bowels irritating then- centripetal nerve fibres : the irritation 

 is propagated to the spinal cord, which reflects it upon the roots of the cervical 

 sympathetic nerve, by which it reaches the blood-vessels of the retina, produces 

 then- contraction, and, as a consequence of this cause of diminution in the amount of 

 blood, an amaurosis. If instead of the reflex action on the blood-vessels, there is 

 an action on the tissues, as in the case of the experiments of Czermak and of Prof. 

 Bernard, the blood-vessels dilate and more blood passes through them. The 

 cornea, for instance, is irritated : its centripetal nerve fibres transmit the irritation 

 to the pons varolii, which reflects it upon the retina, the lachrymal gland, the con- 

 junctiva, &c, more blood is attracted by all these parts, their blood-vessels dilate, 

 and the consequences of a greater amount of blood become manifest — increase of 

 tears, photophobia, &c. 



" The two kinds of effects produced by the nervous system on nutrition and 

 secretion, may co-exist or follow each other, and we have instances of such a com- 

 bination or alternation in cases of neuralgia, of worms, &c." 



Whatsoever physical explanation may be adopted for the many 

 interesting facts concerning the sympathy existing between remote 

 parts of the body, it will be admitted that the subject is one of 

 amazing importance, and considering its importance, it is surprising 

 that so little has been done by physiologists and practitioners to 

 develop its manifold relations in health as well as in disease. 

 Although more than once regretting that his space does not allow 

 him "to enter in greater developments" on this subject, Dr. Brown - 

 Sequard deals with it at considerable length, and in some respects 

 treats it with great originality. In speaking of the morbid changes 

 in the nutrition of the brain, of the spinal cord, and of the organs of 

 sense, produced by an irritation of some centripetal nerve, he shows 

 that insanity, epilepsy, chorea, catalepsy, extasis, hydrophobia, hysteric 

 and other varieties of nervous complaints, may be the result of a 



