650 SCIENCE PROGRESS 



agreement with Tissot's observations, that at the moment when 

 chloroform inhalation stops arterial blood contains an excess 

 of the drug when compared with venous blood, but the 

 difference between the amount of chloroform in arterial and 

 venous blood after regular respiration is established is practically 

 the same. 



A sufficient and satisfactory explanation of the anaesthetic 

 process probably cannot be given at present, but some con- 

 ception of the anaesthetic state produced by the inhalation of 

 chloroform vapour at about 2 per cent, may be attempted. It 

 is true that data for this have been obtained by experiments 

 on cats, but it is allowed that the phenomena shown by this 

 animal during anaesthetisation closely resemble what is seen 

 in man. The blood at first rapidly becomes charged with 

 chloroform, which is held almost entirely by a protein or pro- 

 teins of the red corpuscles. The respiratory centre or centres 

 are at first stimulated, but these become affected quite early, 

 and then discharge pulses less frequently and less efficiently 

 than in a normal animal. In the dog especially, and to a less 

 extent apparently in the cat, this behaviour of the centre is 

 secondary to a weakening, or almost a cessation, of the activity 

 of the heart. From this inhibitory effect the heart escapes, 

 somewhat easily in the cat compared with the dog. The con- 

 dition just described occurs early, within the second to the fifth 

 minute, and may be considered as the first danger point in 

 anaesthesia. In consequence of the slow and shallow respira- 

 tions, the percentage of chloroform in the blood falls, either 

 owing to a diminished intake of vapour or to the cells of the 

 body storing up the drug at the expense of the blood, or because 

 the elimination of the drug is as rapid, or more rapid, than the 

 assumption. But the last cannot be the explanation, for the 

 rate of elimination is by no means so rapid as is the assumption. 

 The fall is, therefore, due largely to the disappearance of chloro- 

 form into the cells of the body, which, in virtue of their proteins, 

 are capable of forming loose chemical combinations or aggrega- 

 tions with the drug. The cells are, in consequence, poisoned in 

 varying degree. When the first danger point is safely passed, 

 the respiratory movements improve in frequency and vigour, 

 and this may be considered to represent a continuation of the 

 initial stimulating effect of the drug, which was masked by 

 the occurrence of a danger point. Thereafter the chloroform- 



