444 Messrs. G. A. Buckmaster and J. A. Gardner. [July 11, 



portion of a much larger number of observations, some of which were incom- 

 plete and only partly serviceable from the inevitable bursting of tubes, which 

 may occur in carrying out a series of Carius' determinations for chlorine, the 

 results of our experiments show that the amount of chloroform in arterial 

 blood of cats at the stage of disappearance of conjunctival reflexes varies 

 between 14 and 27'6 milligrammes per 100 grammes of blood. This amount 

 varies with the individual animal, a fact noticed by others who have worked 

 with dogs. This probably depends on the condition of the animal in the 

 widest sense of the term ; thus some were male, some female, and we 

 were also in many cases ignorant whether the animals had been recently fed 

 or the opposite. The ages of the animals were also unknown. Eeference to 

 the tables shows that body-weight is without influence on the percentage of 

 chloroform in the blood necessary to produce anaesthesia. 



An examination of Curves A, B, C, and D, shows that the rate of induction 

 of anaesthesia varies for different individuals. This does not appear to be 

 altogether dependent upon the percentage of chloroform in the inspired air, 

 but is a feature peculiar to each individual animal. It can be seen from 

 Curve D that the two upward slopes of the curve are closely similar in form 

 in the same animal. In this curve, constructed from an experiment during 

 which a constant percentage of chloroform was inhaled, the lethal point is 

 raised during the second anaesthetisation — in fact, all the corresponding points 

 of the second slope are higher than for the first. The explanation of this, 

 which is a feature we have often noticed, might be that the first anaesthetisa- 

 tion is assisted by some ether which still remains in the animal. But this 

 supposition is not confirmed by a consideration of Curves B and C. We are 

 inclined to attribute the shifting-up of the second part of the curve and the 

 raised lethal point to the loss of blood taken during the course of the experi- 

 ment, as more blood was abstracted from the animal in Curve D than in 

 experiments Curves B and C. The effect of removal of blood markedly 

 alters the lethal dose in blood, a fact made quite evident in Curve E. How- 

 ever, at this stage of our work we do not propose to offer the suggestion that 

 loss of blood is the only factor which raises the lethal dose, as we are still 

 engaged in experiments devised to ascertain the progress of chloroform 

 anaesthesia in animals under varied physiological conditions. 



The lethal dose which arrests respiration in cats is also variable, and 

 averages about 40 milligrammes per 100 grammes of blood, and it 

 will be seen from the Tables that a narrow margin exists between the 

 weight of chloroform in blood at the moment of anaesthesia (loss of con- 

 junctival reflexes) and cessation of respiration. The lethal dose of Curves B 

 and C is slightly higher in the second anaesthetisation than in the first 



