THE RABBIT. 295 



until a small portion of the cord is exposed ; then, 

 inserting the forceps between the medulla ob- 

 longata and the occipital bone, remove the roof 

 of the skull and expose the brain. Great care 

 will be required to do this without injuring the 

 brain, especially in the region just internal to 

 the external auditory opening, where a lobe of 

 the cerebellum (see § 477) will be found embedded 

 in a deep pit of the skull wall. Note as you 

 proceed ; 



162. The dura mater, a tough fibrous membrane lining 

 the cranial and spinal cavities : it is continued inwards 

 between the cerebral hemispheres (§ 480) as the falx 

 cerebri, and between the cerebrum and cerebellum as 

 the tentorium : it is sometimes torn away with the 

 fragments of bone, sometimes left adhering to the brain : 

 in the latter case it is advisable to dissect it away from 

 the dorsal surface of the organ before attempting its 

 removal. 



163. The pia mater,a delicate shining membrane closely 

 investing the brain and cord, and abundantly supplied with 

 blood-vessels. 



164. As in the Pigeon (p. 221, § XXV.), the brain com- 

 pletely fills the skull cavity, the space between the dura 

 mater and pia mater being reduced to a minimum. 



XVI. Cut through the spinal cord about a quarter of 

 an inch beyond its junction with the brain : care- 

 fully lever up the brain with the handle of a scalpel, 

 and cut through all the nerves proceeding from it, 

 working from behind forwards : dissect away the 

 olfactory lobes (§ 483) from their attachments. 

 Remove the whole brain and place it in alcohol, 

 or, better, in saturated solution of zinc chloride, 



