6i6 THE POPULAR SCIENCE MONTHLY, 



recognized them by the sound of their voices. He even forgot his 

 own appearance, and, being in a large public gallery, and seeing, as he 

 supposed, some one in a doorway barring his passage, he stepped for- 

 ward to ask the stranger to let him pass, when by the motions he real- 

 ized that it was his own figure seen in a large mirror. This loss of 

 visual memory extended to memories of his childhood as well as to those 

 acquired recently. It interfered much with his power of reading. In 

 reading a book or in adding a column of figures it was necessary for 

 him to have recourse to movements of articulation of his tongue and 

 lips in order to understand what he read or in order to add. While 

 formerly he could remember easily what he read, he now was obliged 

 to read aloud anything he desired to commit to memory, and thus to 

 learn it by impressing his auditory memory. An interesting detail of 

 the affection was the fact that in his dreams he no longer saw objects, 

 but merely heard sounds or words.* 



Thus he had been deprived entirely of one class of memories, while 

 all others were still at his command. As a consequence, there had 

 come about a complete change in his character, which can easily be 

 understood when one considers how largely one's thinking is made up 

 of the comparison of one set of memories with another, and how fre- 

 quently the whole circuit of one's thoughts and actions centers about 

 one group of memories. This man was an artist, and in a moment all 

 the powers, the result of long study and labor, which enabled him to 

 perform and enjoy his life-work, were taken away. In this case, as 

 in the first one related, the disease must have been situated in that 

 part of the brain where visual memories are stored, viz., in the poste- 

 rior part. 



Such a loss of visual memories may be temporary, as is well illus- 

 trated by the case of a city district messenger-boy, who found on 

 several occasions that he suddenly lost his way and could not recog- 

 nize streets with which he was usually familiar, so that he was obliged 

 to ask a policeman to take him to his home ; where, however, in the 

 course of a few hours he recovered his memory of places and of faces 

 which he had lost. In this case, which may be regarded as one form 

 of epilepsy, the loss of memory can be explained by the hypothesis 

 that a spasm of the arteries occurred in the posterior part of the brain, 

 just as such a spasm in those of the face gives rise to a sudden pallor. 



Visual memories are not the only ones to be temporarily or per- 

 manently lost. There is another class of cases whose study gives 

 unmistakable evidence of the localization of memories in that part of 

 the brain in which the original perception occurred. It has been 

 stated that the auditory nerve sends a tract to the lower lateral portion 

 of the brain (the temporal region), and that destruction of this region 

 in animals gives rise to deafness. "When this part is injured by dis- 

 ease in man, a peculiar condition is observed, known as word-deafness. 

 * This case is reported in the " Progrfes M6dicale," July 18, 1888. 



