THE BRAIN. 



313 



Fig. 152. 'double cord from the thorax of 



the pupa of sphinx ligustri, 

 showing the respiratory gan- 

 glia and nerves between the 

 ganglia 2, 3, 4, and the sepa- 

 rated cords of the locomotive 

 system. Fig. 153, C, view 

 of the two systems combined, 

 showing their arrangement in 

 the larva : , ganglion of the 

 ventral cord ; , fibrous tract 

 passing over it ; c, <?, respira- 

 tory system of nerves, distinct 

 from both. 



Having thus presented the views of Dr. Carpen- 

 ter respecting the analogy between the ventral cord 

 of the articulata and the spinal cord of the verte- 

 brata, I should next continue the explanations 

 which this pjiysiologist has offered of the connec- 

 tions and relations of the sensory ganglia ; but this 

 can not be conveniently done until we have passed 

 through the description of the organs at the base of 

 the brain. 



Thoracic portion of cord of 

 sphinx ligustri. 



CHAPTER XVI. 



OF THE BRAIN. 



The Brain: its Structure. Its Motor and Sensory Parts, Hemispheres, and Commissures. 

 The Sensorium. Variations of the Hemispheres in Size and Weight. Instrumental Nature 

 of Cerebrum. The Cerebellum: its Structure and Functions. Co-ordinates muscular Motions. 

 Connection with Amativeness. Phrenology. Conditions of Action of Brain. 



Symmetrical Doubleness of the Brain. Function of each Half, and of both conjointly. Independ- 

 ence and Insubordination of each Hemisphere. Double Thought. Alternate Thought. Senti- 

 ment of Pre-existence. Loss of Perception of Time. 



THE cerebrum and cerebellum, being organs additional to the spinal 

 cord, and developed, as has been shown in the last chapter, n 



. \ ' . ' General view 



upon it, the cord being able to discharge its own functions of structure of 

 independently of them, we shall find it at once the most brain> 

 natural and most commodious method to consider their structures as 

 arising out of its structure, and their functions as having relation to its 

 functions. 



A general idea of the structure of the brain as an appendage to the 



