692 THE POPULAR SCIENCE MONTHLY. 



forth that outward activity which is peculiar to life ; it droops, no in- 

 tellectual manifestations occur, no impressions from light or sound are 

 felt ; but let a current of cool, fresh air touch the face, and life revives, 

 the heart resumes it movements, color comes to the cheeks, and the 

 phenomena of intellect and sensation reappear in the inverse order of 

 their cessation. The English surgeon, Astley Cooper, produced simi- 

 lar phenomena in dogs by compressing the arteries of the brain at the 

 neck ; the animal fell into utter insensibility, and seemed to die. On 

 suspending compression, cerebral life immediately returned; yet this 

 was but an imperfect representation of what takes place in fainting. 

 It was reserved for one of our own physiologists to go more deeply 

 into the mechanism of the phenomenon. To bring life back again for a 

 moment to a head severed from the body, and to restore it by the ar- 

 terial blood, this was the problem which Brown-Sequard proposed and 

 solved. The details of this memorable experiment were these : A dog 

 is beheaded, and the head, still warm, separated from the trunk at the 

 junction between the neck and chest. The evidences of life disappear 

 by degrees, the eye losing its expression last. An electric current 

 sent through the remaining part of the spinal cord no longer excites 

 any contractions, the respiratory movements of the nostrils and lips 

 cease entirely. After ten minutes have elapsed, Brown-Sequard ad- 

 justs to the four arteries of the head an arrangement of tubes commu- 

 nicating with blood deprived of its coagulable part, and charged with 

 oxygen. By the help of artificial mechanism, imitating the action of 

 the heart, the experimenter makes the blood circulate throughout the 

 brain and spinal cord. A very few moments pass before irregular 

 quiverings give life to the face, growing more decided, and at length 

 movements reappear in all the muscles, and the eyes resume motion. 

 " All these movements," says Brown-Sequard, " seem directed by the 

 will." The experiment was continued for a quarter of an hour, and 

 during all that time the vital manifestations and the appearance of 

 their being voluntary continued. They soon ceased after the injection 

 was stopped, and then followed the group of phenomena observed in 

 dying, the pupil contracted and again dilated, and the last effort of 

 life was a sti'ong convulsion of all the facial muscles. 



The naturalist experiences the strongest emotions at the sight of 

 so extraordinary a spectacle. The physician now understands the ne- 

 cessity of contact between arterialized blood and the matter of the 

 brain. He knows why a reclining position is proper in cases of faint- 

 ing, giving easy access for the vivifying fluid to the brain. He knows 

 that by throwing water on the face he will act upon the nervous cen- 

 tres, reanimate the movements of the heart, and cause circulation of 

 blood in the mass of the brain. The philosopher asks himself one of 

 those questions which are as old as the world, and more than ever of 

 present interest, since the animated discussions of Barthez and Ga- 

 banis : Does or does not organized matter engender the phenomena 



