378 DISSECTION OF THE RABBIT. 



X. DISSECTION OF THE BRAIN. 



Tha brain should be removed directly after the rabbit is 

 killed, and placed at once in strong spirit, as it decomposes 

 rapidly. It is well to put a loose pad of cotton wool in the 

 bottom of the bottle, and place the brain upon it, in order to 

 prevent flattening from contact with the glass, and to ensure 

 free access of the spirit to all parts of the surface ; the brain 

 should be turned over after it has been a few hours in spirit. 



To remove the brain, first shin the head ; then expose the 

 brain by snipping away, with the hone forceps, the roof and 

 sides of the skull, beginning at the foramen magnum, and 

 working forwards. Take special care in the region of the ears 

 to avoid injury to the floccular lobes of the cerebellum, which 

 are lodged in the floccular fossce of the periotic bones (p. 301).. 



Having completely removed the roof and sides of the 

 cranium and cut through the dura mater, a tough fibrous 

 membrane which lines the cranial cavity, cut across the spinal 

 cord about half an inch behind the foramen magnum, and 

 turn out the brain from behind forwards, lifting it up gently 

 with the handle of a scalpel. 



Note and identify the several nerve-roots as you do so, and 

 cut through them in order, close to tha skull-wall, so as to 

 leave as much of the roots as possible attached to the brain. 



Place the brain in spirit at once, handling it with great 

 care, as it is very soft and easily damaged. Leave it in spirit 

 for three or fowr days, and then dissect it as described below. 



The several divisions of the rabbit's brain are the same 

 as those of the brain of a dog-fish, the most important 

 differences between the two being, (1) the great size of the 

 cerebral hemispheres, which overlap and conceal the dorsal 

 and lateral surfaces of the thalamencephalon and optic lobes ; 

 (2) the greater size and more complicated structure of the 

 cerebellum ; (3) the much greater development of the trans- 

 verse commissures, connecting the two halves of the brain 

 with each other. 



