158 DEPRESSANTS TO CENTRAL NERVOUS SYSTEM 



convulsions of the young and may be of considerable service when 

 administered in an enema. 



It has been used externally to stop feather pulling of birds and 

 to prevent bandage chewing with dogs. 



VALERIANA — VALERIAN 



Valerian is the rhizomes and roots of Valeriana ojficialis, a plant 

 of Europe. It contains a volatile oil and valeric acid. 

 Preparations and Doses. 



Valeriana. II. and C. §j — ij ; 30 — 60. D. gr. x — 5j ; 0.6 



—4. 

 Tinctura Valerianae. D. Zaa — j; 2. — 4. 

 Tinctura Valerianae Amnioniata. D. 3ss — ^j ; .2. — 4. 



Action and Uses. Valerian has the usual effect of a volatile oil 

 and so is carminative. It slightly stimulates the heart, vasamotor 

 and respiratory centers. It has been recommended as an antispas- 

 modic and antihysteric in human medicine, but since it produces 

 this action by stimulating the highest centers which exert psychic 

 control, it must be of doubtful value in veterinary medicine. 



The valerates (valerinates) of zinc, iron, quinine and ammonium 

 do not have carminative action and exert but little of the action of 

 the liquid preparations. Average dose. T). gr. ij — v; 0.13 — 0.3. 



Valerian and the valerates have been especially recommended 

 for the treatment of chorea in dogs but the results have not been 

 satisfactory. 



ANESTHETICS 



Theories of Narcosis. Several theories have been advanced as 

 to how the narcotics reach the cerebral cell contents and anesthesia 

 is produced. The most generally accepted of these are : 



1. Meyer-Overton. This was advanced by Meyer and Overton 

 separately. They believe that these drugs exert their chief action 

 upon the central ner\'ous system, because they are taken up by the 

 fats and lipoids, lecithin, cholesterin, cerebrin, etc., which are 

 abundant there, and are held in contact with the cell structures. 

 According to these men the anesthetic properties increase with the 

 solubility in. fats and lipoids and insolubility in water. This rela- 

 tionship of solubility of hypnotics and anesthetics is at least very 

 striking and there seems to be considerable evidence to support this 

 theory, which is the one generally accepted. It shows simply how 

 the brain cell is reached, but does not explain the action upon it. 



2. Moore and Roaf. This theory is based upon the assump- 

 tion that anesthesia or narcosis is due to a change in the protoplasm 

 of the cerebral cells by the formation of loose compounds of ether, 



