RESEARCHES ON CHLOROFORM ANAESTHESIA 639 



or surfaces of separation, so arranged that normally certain ions 

 could traverse the membranes and others could not, while after 

 chloroform these membranes or surfaces were destroyed. A 

 simple combination of proteids, as in Moore and Roafs theory, 

 or with lipoids, according to Meyer and Overton, with chloro- 

 form would therefore be insufficient to account for the pheno- 

 menon of anaesthesia. 



The ANiESTHETic AND Lethal Quantities of Chloroform in 



THE Blood. 



In i860 Lallemand, Perrin, and Duroy stated that 100 

 grammes of blood contained i cc. of chloroform vapour. This 

 was the lethal amount. In 1883, from the results of seven 

 experiments, Grehant and Ouinquaud concluded that 50 milli- 

 grammes of chloroform in 100 grammes of blood was the 

 anaesthetic quantity, which was only slightly less than the 

 amount present at the lethal stage. It will be seen subsequently 

 how very exact were both these determinations. Pohl's work 

 in 1890 introduced a new method for the determination of 

 chloroform in blood, and his chief conclusions were that the 

 quantities of chloroform in the arterial blood of dogs during 

 anaesthesia might vary. In some cases 100 grammes of blood 

 contained "05 gramme, in others only "029 or '018 of chloroform. 

 The average lethal amount was '035 gramme. Pohl also 

 recognised that the lethal and anaesthetic amounts closely 

 approximate one to the other. For about sixteen years no 

 further researches were undertaken in connection with this 

 question, but it was from time to time made abundantly evident 

 that an accurate determination of the chloroform-content of 

 blood was one of difficulty, owing to the tenacity with which 

 the drug was held by the blood, so that it could only in part 

 be recovered from that liquid or from the tissues of the body. 

 During 1906 several French observers, and Buckmaster and 

 Gardner in this country, have renewed this inquiry, and 

 though the methods which have been employed in France and 

 England are quite dissimilar, there is a fair uniformity in the 

 results. The determinations bf chloroform in the blood, made 

 by M, Nicloux, St. Martin, J. Mansion, and Tissot, depend 

 upon the titration of the chloroform as chlorides, which are 

 obtained from the blood by distillation with alcohol, rendered 



