308 REPORTS ON THE STATE OF SCIENCE. 
the chlorine-content of the blood before and after anesthetisation with 
chloroform was calculated, and this gave a figure which could be ex- 
pressed as chloroform. The whole method is an entirely new one, and 
has never been employed by earlier observers. In exactness it is 
believed to be preferable to those methods where the determination is a 
volumetric one with an end point which depends upon a colour reaction. 
Most of these experiments have been carried out on cats, while other 
observers have generally carried out their investigations on dogs. The 
chief conclusions arrived at were that the amount of chloroform in 
arterial blood at the moment when some definite reflex action disappears 
varies with different individuals. The same is true for the lethal amount 
in the blood; but a consideration of all the experiments taken together 
shows that only a narrow margin exists between the weight of chloro- 
form in the blood at the moment of anesthesia (loss of conjunctival 
reflexes) and the cessation of respiration (lethal amount). 
The conclusions are represented in the following table in comparison 
with the results of previous observers :— 
Rearaal Anesthetic amount Lethal amount 
Observer, ; of CHCl;. of CHC];, 
mg. mg. 
Grébant and Quinquand, 1883 dogs 50 — 
Pohl, 1890. : c ess 18-50 : . . 35 
Waller and Wells, 1903 . cats Sip os 4 ¥ grad 
Nicloux, 1906 ° : . dogs 50. : : - . 41-70 
Tissot, 1906 . ; . s 34-40. ‘ : fs . 60-105 
J. Mansion and J.Tissot,1906 _,, { oe } yen etn ls = 
Buckmaster and Gardner,1906 __,, 16-41 reflexes just gone. 61-69 
3 i ” cats 14-27°5 reflexes just gone. 40 
The Rate of Assumption of Chloroform by the Blood.—It is a 
familiar fact that when chloroform is inhaled the respirations may 
rapidly diminish in depth and frequency, or even actually stop within a 
few minutes. In the case of cats it is exceedingly rare not to see this 
effect on a respiratory tracing. Any individual animal may exhibit this 
phenomenon in different degrees, and cessation of respiration may be 
permanent unless resort is had to some means of artificial respiration. 
When the same animal is anesthetised several times with the same 
percentage of chloroform vapour, this condition, which may be con- 
sidered to indicate the first danger-point in chloroform anesthesia, 
occurs at the same time, and presents a constant type of impaired 
respiration. 
In our experiments, which were carried out on cats, small quantities 
of blood were withdrawn from time to time from an artery during the 
induction of anzsthesia with known percentages of chloroform vapour 
and air. The determination of the quantity of clHloroform 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-anesthetic period, or initial 
stages of anesthesia, 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 anesthesia occurs, 
because the quantity of chloroform in the blood directly or indirectly 
affects the respiratory nerve-centres of the brain. In consequence of 
