LANGUAGE AND BRAIN DISEASE. 777 



by sound. When it is aroused by impulses coming from the ears, 

 the sensation of sound occurs ; but when it is aroused by nerve- 

 currents, not from the ears, but from other parts of the brain, we 

 have only the memory of sound. For a word to be understood, 

 the auditory center alone is not sufficient. The sound must 

 awaken the memories of other sensations. The word " orange," 

 for instance, has a meaning because the auditory center, when the 

 word is heard, arouses in the visual center the memory of the 

 color and form of an orange ; in the centers for touch, tempera- 

 ture, posture, and muscular sense, the memory of the sensations 

 which occur when the fruit is grasped by the hand ; in the cen- 

 ters for smell and taste, the memory of its peculiar odor, flavor, 

 and tartness. These sensations are said to be associated with the 

 sound of the word, and together with it they constitute the con- 

 cept " orange." The nerve-currents passing from one center to 

 another are called association impulses. If we have often eaten 

 oranges, and at the same time heard the name, the auditory center 

 whenever it perceives or remembers the sound will send vigorous 

 impulses to the other centers, and the idea will be vivid. But if our 

 experience of oranges has been very limited, or if the name has 

 been rarely heard, or if instead of the correct name a merely similar 

 sound has been heard, the association impulses will be sent slowly, 

 feebly, and uncertainly, so that the idea will be vague. Prompt and 

 strong associations should be cultivated as a means of securing 

 clear and vivid ideas. The auditory center is the first language 

 center to be developed. A child hears soon after birth, and to- 

 ward the end of its first year the sounds of a few words are un- 

 derstood. Up to this time no words have been uttered, but the 

 child now begins to imitate the sounds it understands and soon 

 can use them. This requires the co-operation of the motor speech 

 center, M, which by connecting fibers and the currents they carry 

 combines the simpler movements of the vocal organs to form 

 words. In the case of Gambetta, who was a loquacious politician 

 and very successful orator, this center was excessively developed, 

 though the brain as a whole was not remarkable. On the con- 

 trary, a study of the brain of the distinguished statistician, Ber- 

 tillon, who was diffident and reticent, showed a high degree of 

 general development, with an almost rudimentary motor speech 

 center. 



In speaking, the guidance of the auditory center is necessary. 

 The sound of a word must be remembered when it is uttered. On 

 the other hand, the effort of the motor speech center to utter a 

 word reacts upon the memory of the sound, causing it to be more 

 vivid. In the main the two centers work and develop together, 

 but the auditory center is the more independent and fundamental. 

 If a child becomes deaf, even as late as the tenth or eleventh year, 



