280 MESSRS. F. GOTCH AND V. HORSLEY 



posterior part alone, and in most cases opposite to the side to which the excitation 

 was applied. 



CHAPTER III. DETAILED DESCRIPTION OF THE METHODS EMPLOYED IN 



THE PRESENT RESEARCH. 



The description of the methods may be best effected by considering, in succession : 



1. The method of anaesthesia employed. 



2. The operative procedure. 



3. The recording and exciting apparatus. 



4. The general procedure and the precautions used. 



SECTION I. METHOD OF ANAESTHESIA. 



The anesthetic employed in these experiments was, in almost all cases, ether, the 

 exceptional cases being those in which some bronchial or nasal catarrh rendered it 

 advisable to substitute chloroform, this latter giving a more even and steady narcosis, 

 though at greater risk to the animal. 



The physiological action of ether has received considerable attention lately, arid a 

 few points in connection with it are of sufficient importance as bearing upon our 

 experiments to warrant a more detailed notice. 



In the first place, it has been shown (HOOPER, SEMON and HORSLEY, BOWDITCH, 

 and others) that ether when present in the circulating blood through inhalation, 

 appears to have a distinctly differential effect upon the two kinds (red and white) of 

 muscle, or upon their innervation, i.e., centres, fibres, or nerve endings. 



Further that the direct application of the liquid or vapour of ether to the trunk of a 

 nerve causes paralysis of its physiological conductivity.* (HOOPER and BIEDERMANN.) 



The investigations of FLOl^RENst in 1847 had elicited the fact that the inhalation 

 of ether produced physiological effects, in which the functional activity of the reflex 

 centres was abolished- before that of the conducting nerve paths, and this has been 

 substantiated by the work of other investigators. 



It is with special reference to the action of ether upon these two structures that 

 the present remarks are introduced, since, with the exception of the few experi- 

 ments in which we employed the graphic method, our work has been entirely confined 

 to the study of the changes in nerve centres and nerve fibres. 



It was consequently of primary importance for us to know to what extent the 

 inhalation of ether has a differential action upon nerve centres as distinct from nerve 

 fibres. 



In this connection experiments (HORSLEY and SPENCER) have shown that the 



* BIEDERMANN, ' Wien, Akad. Sitzber.,' vol. 97, 3 Abth., 1888. 

 t FLOUKENS, ' Comptea. Keudus,' vol. 24, 1847, p. 101. 



