ON ANAESTHETICS. 309 
the respirations being slower and shallower, the amouiit 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 
(Amount of CHC), (in milligrammes per 100 grammes) 2 
Time /0 mins. 20 
Plotted curve of the amount of chloroform found in the blood of a cat during the first hour of 
administration of chloroform at between 3 and 4 per 100 as determined by densimetry. (Proc. Roy. Soc., 
vol. Ixxix. p. 562.) 
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 anesthetic 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 between the amount of chloroform 
present in the blood and what is found at the lethal point is very small. 
The state is far from one of safety, and the animal may suddenly die 
at any moment should any disturbing factors come into play. The 
whole of this period is a danger period. In the experiments quoted the 
percentage of inspired chloroform was maintained constant, but it is 
evident that the contention of those anesthetists who have insisted that 
after anesthesia has been established this can be and should be main- 
tained with a much smaller amount of chloroform vapour rests upon a 
sound basis. 
The Function of the Red Blood-corpuscles in Chloroform 
Anasthesia.—Experiments undertaken in order to ascertain how the 
anesthetic distributes itself in the blood between the corpuscles and ~ 
plasma proved to be exceptionally difficult. The separation of the 
corpuscles was accomplished by centrifugalising tubes of blood sur- 
rounded with ice, so as to hinder any clotting. Their conclusions, that 
chloroform is very firmly held by the blood of an anzsthetised animal, 
are in accord with all other observers. But it was also found that 
