644 SCIENCE PROGRESS 



to hydrochloric acid. The chief new facts elicited by this 

 work show, as might have been anticipated, that the rate at 

 which chloroform is absorbed varies directly with the extent 

 to which the lungs are ventilated. The slow and shallow 

 respirations which occur so early in chloroform anaes- 

 thesia also stand in relation with a maximal retention of 

 chloroform in the body, but how much of this is actually in 

 the blood could not be stated. It is, however, abundantly clear 

 that the minimum amount of chloroform in the expired air is 

 found during the second minute, and from that period onwards 

 the amount escaping from the body slowly rises. In a series 

 of experiments, each lasting ten minutes, it was also observed 

 that the amount of chloroform absorbed increased with the con- 

 centration of the drug in the inspired air, but the amount was 

 not in proportion to the concentration. 



In the experiments of Buckmaster and Gardner, 1 which were 

 carried out on cats, small quantities of blood were withdrawn 

 from time to time from an artery during the induction of anaes- 

 thesia with known percentages of chloroform vapour and air. 

 The determination of the quantity of chloroform in these samples, 

 ten or twelve in each experiment, afforded the data from which 

 curves could be constructed. In all of the curves the same 

 general features were seen. In the pre-anaesthetic period, or 

 initial stages of anaesthesia, at a time when the individual is 

 conscious, the chloroform-content of the blood rises with great 

 rapidity to a value which approaches a maximum. During this 

 period, which occupies the first few minutes, the first danger point 

 in anaesthesia occurs, because the quantity of chloroform in the 

 blood directly or indirectly affects the respiratory nerve-centres 

 of the brain. In consequence of the respirations being slower 

 and shallower, the amount of chloroform in the blood falls, but 

 the fall is also due to the exit of the drug from the blood into 

 the tissue-cells of the body. When the animal has passed this 

 first stage the amount of chloroform again quickly rises towards 

 a maximum value, and an equilibrium between the factors which 

 determine the amount of chloroform in the blood appears to be 

 obtained, the processes of intake and output of the anaesthetic 

 at the surface of the lung going on side by side. In other 

 words, a state of equilibrium is reached, which persists for a 

 considerable period, and throughout this period the difference 



1 Proc. Royal Soc, B, vol. lxxix. 1907. 



