618 THE POPULAR SCIENCE MONTHLY. 



How was it that I was able confidently to advise the policeman 

 about this poor woman, though he was no doubt very experienced in 

 this sort of cases? What aid did experimental inquiry give me in 

 arriving at my conclusion ? 



Well, in the first place, I knew that the paralysis was restricted to 

 voluntary movements, without the motions belonging to organic life 

 being in the least interfered with. Vivisections of the earliest times 

 informed me that this was quite possible as a result of some injury of 

 the nerve-centers, and experiments of more recent date enabled me to 

 exclude a large part of these centers from being the seat of the lesion. 

 That there was no local injury of the spinal cord in the dorsal region 

 I knew, both from the loss of consciousness and from the fact that the 

 I'eflex action of the lower limbs was not intensified, and vivisections in- 

 formed me they would have become so had this been the case. I could 

 see by the movement of the left leg that only one side of the body 

 was paralyzed ; and then the look of the face distinctly showed that 

 part of the seventh cranial nerve, which Charles Bell's vivisections 

 taught me to know to be motor in function, was paralyzed. This fact, 

 together with the ready reflex action of the eyes and the sound side of 

 the face, which I knew by vivisection required unimpaired sensory 

 nerves, showed me that it could not be a case of profound toxaemia 

 such as the policeman supposed to be possible. I knew by vivisec- 

 tions performed by many English physicians and physiologists, some 

 of whom are still among us, that the second heart-sound depended on 

 a certain action of the aortic valves. Not hearing the familiar sound, 

 I concluded that the aortic valves must be diseased. Experiments on 

 living animals concerning coagulation of the blood within the vessels 

 informed me that when the lining coat of a blood-vessel, or the heart, 

 is diseased, little clots are often formed at the diseased or injured part. 

 I knew, further, from Virchow's classical experiments on living ani- 

 mals, that emboli introduced into the arterial blood-current often be- 

 come impacted in the middle cerebral artery, and that the embolic 

 blocking of a brain-artery, by shutting off the blood from the area it 

 supplied, caused a sudden arrest of function of the part. Although the 

 nerves going to the various paralyzed muscles arose from very differ- 

 ent regions of the cord and brain, I know by vivisections that there is 

 a part of the cortex of the brain the injury of which would cause them 

 all to be powerless. Clinical observation and pathological anatomy 

 would have informed me that it was probably a brain-lesion ; but, had 

 it not been for the light thrown by vivisection on the few facts I was 

 able thus hurriedly to observe, I should not have been much wiser than 

 any other by-stander, and could only have agreed with them that it was 

 a " stroke " of paralysis. 



Now let us consider a surgical case. The other day I mentioned 

 some of the old methods of operation, when buttons of vitriol, caus- 

 tics, steel compresses, boiling oil, hot irons, a copious receptacle for 



