580 Messrs. G. A. Buckmaster and J. A. Gardner. [July 19, 



chloroform it would seem that there is an initial stimulating effect which 

 may approach the lethal value, but that if this is not actually attained the 

 stimulating effect, which was masked, persists as a recognisable after-effect 

 when the first danger-point has been passed. Thereafter the chloroform- 

 content of the blood approximates to a maximal value, which is maintained 

 until asphyxia takes place (maximum value). 



If the rate of elimination were more rapid than the rate of intake, or even 

 -equal to this, it would not be easy to understand why this maximal value is 

 .-so rapidly reached or maintained, and for these reasons it appeared important 

 that we should study the rate at which chloroform was eliminated during 



anaesthesia. 



Method. 



All the experiments were performed upon cats, which were anaes- 

 thetised by ether, and the necessary operations performed after an 

 injection of hirudin into the femoral vein in quantity sufficient to delay the 

 coagulation of the blood during the time of the experiment. After the 

 animal had so far recovered from ether that the reflexes had reappeared but it 

 was still under the influence of the drug, chloroform of about 2 to 3 per cent, 

 was administered from a Woulff s bottle of the form described in our former 

 papers. The inhalation was stopped in some cases when the asphyxial point 

 was reached, and in other cases at an earlier point during the period we have 

 described as the second stage of anaesthesia. Immediately the inhalation of 

 chloroform was stopped, samples of blood were abstracted from the central 

 end of one carotid artery or from the cephalic end of the external jugular 

 vein, or from the side tube of a short T-piece connecting the cephalic and 

 thoracic end of the vein, or by the introduction of a tube several inches 

 in length along the vein, so that a sample of blood could be taken from the 

 right auricle at definite intervals of time. In some experiments only arterial 

 blood was examined, in others only venous, and in other cases samples were 

 taken simultaneously from both the artery and vein. The methods of collecting 

 and analysing samples of blood were those fully described in our former 

 papers. In some experiments, however, it was found more convenient to 

 abstract the venous blood from the cannula by means of a syringe. During 

 the entire course of any experiment the respirations were recorded by a 

 tambour placed on the ensiform cartilage. 



From all our experiments we have selected five typical examples, details 



of which are given. 



Experiment I. 



Cat. Weight 3 - 7 kilogrammes. Respiration recorded by tambour on 

 abdomen. Samples from carotid artery. 



