592 TEXT-BOOK OF PHYSIOLOGY 



Language. Language may be defined as the expression of ideas by a 

 succession of motor acts and may be divided into (i) spoken language (ar- 

 ticulate speech), and (2) written language. The expression of ideas by j 

 words (speech) and by verbal signs (writing) depends primarily on the power 

 of reviving images or memories of objects, words, letters, numbers, etc., seen 

 and heard, and secondarily on the power of reviving the images or memories 

 of the muscle movements which were previously employed in an effort to 1 

 imitate or reproduce the sounds of objects, words, letters, etc. (speech) or 

 the visual impressions by verbal signs (writing). 



For both spoken and written language two phases of activity are to be 

 recognized, viz. : a receptive or sensor and an emissive or motor, 

 i. The Receptive or Sensor Phase. Before language can be acquired by 

 a developing child, impressions of external objects must be made on the 

 visual, auditory and other sense-organs as well, which in consequence 

 lead to the development in the corresponding cortical areas of sensations 

 and ultimately of conceptions regarding the nature of the objects im- 

 pressing themselves on the peripheral sense-organs. 



Thus, through the visual apparatus in its entirety, definite concrete 

 conceptions regarding the shape, size, color, etc., of an object or word, 

 letters and numbers, etc., are obtained. For future use the sensations 

 must not only be perceived but registered or memorized. The memor- 

 ization of the sensations produced by luminous objects, is supposed to 

 be associated with the activities of the cortex on the lateral aspect of the 

 occipital lobe ; the sensations produced by words, letters, and numbers 

 with the activities of the cortex of the supra-marginal and angular con- 

 volutions of the parietal lobe. This is made possible by means of 

 association fibers which unite the primary visual area in and around 

 the cuneus, with the secondary visual areas. That the visual memories 

 " are associated with the previously mentioned convolutions of the parietal 

 and occipital lobes is apparent from the fact, that if they are destroyed 

 by disease there is a loss of these memories even though the individual 

 sees the objects as formerly; but though seeing them they cannot be 

 remembered or recalled. To this condition the terms word and object 

 blindness have been given. 



Coincidently with the development of visual sensations and their memori- 

 zation, the child receives through the auditory apparatus in its entirety, 

 definite concrete conceptions regarding the intensity, pitch and timbre or 

 quality of sounds produced by atmospheric vibrations, due to vibrating 

 bodies; sounds which are subsequently associated with the vocal and articu- 

 lating apparatus of human beings when pronouncing words, letters and 

 numbers, or with objects such as bells, musical instruments, etc. For 

 future use the sensations thus aroused must not only be perceived but like- 

 wise registered or memorized. The memorization of the sensations pro- 

 duced by atmospheric vibrations is supposed to be associated with the 

 activities of the temporal lobe and more particularly of the posterior two- 

 thirds of the super-temporal and medi-temporal convolutions. This is made 

 possible by means of association fibers which unite the primary auditory area 

 with the secondary auditory areas. That the auditory memories are associ- 

 ated with the previously mentioned convolutions is apparent from the fact 

 that if they are destroyed by disease, there is a loss of these memories 



