266 VETERINARY HOMCEOPATHY. 



mater, which is known as the ^^ arachnoid;'' between the two 

 layers of the arachnoid, and therefore intervening between the 

 pia viatcr and the dicra maier, a particular serous fluid is present; 

 the object of this fluid is probably to diminish concussion and 

 generally to afford protection for the soft, delicate material of the 

 brain and cord and prevent injury thereto that might otherwise 

 attend the jar against the hard, bony case. In respect of the 

 nerves, it may be stated broadly that they arise from certain recog- 

 nized centres in the brain and spinal cord, and pass out of the 

 cranial cavity and spinal canal in pairs through special openings 

 (or foramina) and proceed therefrom to their particular destina- 

 tions to be distributed over the whole body ; of the cranial nerves 

 there are twelve pairs; and the spinal nerves are estimated at forty- 

 two pairs. The three membranes already described as the dura 

 mater, the arachnoid and the pia mater will in the future be re- 

 ferred to conjointly as the meninges, it not being necessary to dif- 

 ferentiate between them when treating of them in the inflamma- 

 tory conditions affecting them in the various forms of disease in 

 which they are complicated; but it was deemed desirable to explain 

 how and of what the meninges are composed, as they occupy a 

 rather considerable and important position in some disease con- 

 ditions affecting the brain and cord. 



INFLAMMATION OF BRAIN SUBSTANCES— CEREBRI- 



TIS— INFLAMMATION OF THE MENINGES— 



MENINGITIS. 



Although the true brain substance and the brain coverings may 

 under certain conditions be independently the seat of inflamma- 

 tion it is rare to meet with a case in the horse where, either at the 

 outset or as an ultimate development, both parts are not affected, 

 and this is accounted for by the fact that the disease is generally 

 due to a cause that necessitates their joint implication; injury as 

 the result of external violence or some abnormal prominence in 

 the cranial bones accounts most frequently for these cerebral in- 

 flammations; they may arise in some instances from exposure to 

 the overpowering rays of a tropical sun, or in connection with a 

 specific fever, but in the hor.se this is of rare occurrence. It will 

 therefore be seen that whether the inflammation hz due to violence 

 from without or injury from within the cranial cavity as the result 



