THE REGULATING MECHANISM 207 



through the corpora striata into the peduncles 

 and then downwards in the pons and bulb 

 (where they cross or decussate) ; they then 

 pass down the anterior part of the cord, 

 until they reach the segment or segments 

 of the cord, in which they end by becom- 

 ing related to the great motor neurones 

 in the anterior part of the grey matter (see 

 p. 190). Fibres to and from the cerebrum are 

 related to the deep origins of the cranial 

 nerves. Finally, the cerebrum receives numer- 

 ous fibres from the cerebellum. The physio- 

 logical mechanism of the cerebrum is still 

 obscure. Portions of the grey matter of the 

 convolutions are concerned in the reception 

 of sensory impressions that are translated 

 into consciousness. 



120. Definite districts of grey matter, more 

 especially in the posterior and lateral portions 

 of the cerebrum (temporo-sphenoidal convolu- 

 tions) receive messages that are translated 

 into sensations of touch, pressure, temperature, 

 vision, and hearing. These areas constitute 

 what are termed centres for the special senses. 

 No centre has been identified with taste. 



