440 Mr. J. S. R. Russell. Circumstances under which [May 18, 



Operative Procedure. 



The anaesthetic employed to render the animal unconscious was 

 invariably ether, except in those instances in which the effect of the 

 action of chloroform on the lumbar centres was under consideration, 

 when that anaesthetic was alone made use of throughout the experiment. 



In every instance tracheotomy was performed, and narcosis kept 

 up by allowing the animal to inhale the anaesthetic through the 

 tracheotomy tube. When the effects of the inhalation of certain 

 gases were under observation the tracheotomy tube was connected 

 with a "["-shaped glass tube by means of a short piece of india- 

 rubber tubing ; and india-rubber tubing was connected with the other 

 two limbs of the "J"-tube, by which means it was easy to so arrange 

 that the animal should inhale the particular gas from its reservoir, 

 and exhale into the air of the room, the one tube being connected 

 with the reservoir, and the other left free. 



In those instances in which the heart beats were recorded the 

 right carotid was exposed, opened, and a cannula inserted into it, 

 which in turn was in connexion with a mercurial manometer. When 

 a graphic record of the respiratory excursions was obtained ifc was 

 made by means of a bertambour, whose elastic membranes were 

 attached to a strip of Leslie's strapping which encircled the thorax. 

 From this tambour an india-rubber tube led to a Marey recording 

 tambour by which the respiratory excursions were registered on the 

 cylinder. 



In studying the effects of anaemia of the cord, the abdominal aorta 

 was compressed, either by means of the thumb through the integu- 

 ments, or directly after it had been exposed by dissection. General 

 blood letting was effected by exposing and dividing one or both 

 carotids. 



Intravenous injections were made by injection with a hypodermic 

 syringe into either a jugular or femoral vein, the minute opening 

 made by the needle being closed by a small clip. 



Bisection of the spinal cord was effected by exposing the cord at 

 the level of the roots concerned with the knee jerk, inasmuch as divi- 

 sion of it abolishes the phenomenon, and by means of a delicate thin- 

 bladed knife, making a vertical incision along the middle line of the 

 cord to the extent of two inches, with the root at its midpoint, and 

 extending through to the anterior surface of the cord. In removing 

 a cerebral hemisphere, a small disc of bone was first removed from 

 one side of the cranium by means of a half-inch trephine, and then 

 the opening was enlarged by bone forceps until the whole hemisphere 

 was exposed. The dura mater was then dissected off, and the 

 hemisphere removed en masse, or taken away piecemeal by means of 

 a sharp scoop. 



