92 



Prof. B. Moore and Dr. H. E. Roaf. 



[Oct. 19, 



B. — Experiments on the Relationship between Vapour-pressure and Concen- 

 tration of Chloroform in Emulsions in Saline of the Ethereal Extractives 

 (Lipoids) of Serum and Brain Tissue. 



These experiments were devised with the object of testing whether the 

 alterations in the relationships between vapour-pressure of the anaesthetic and 

 its concentration, as compared with water and saline, found in the case of 

 serum and the tissues, were due entirely to lipoids or ethereal extractives 

 contained in these fluids, or whether part of the effect was due to action of 

 the proteids. The results shown in the curves of figs. 1 and 3, clearly show 

 that a great deal of the action is due to the proteid. 



That a certain amount of the anaesthetic will be taken up by the lipoid in 

 a physical fashion there can be no doubt on account of the high solubility of 

 chloroform and other anaesthetics in such lipoid substances. But we hold 

 that the portion of anaesthetic so taken up and held by the lipoid is passive 

 and not active, and that it is the other portion taken up by the proteid (the 

 existence of which figs. 1 and 3 demonstrate) which is active in paralysing 

 protoplasmic activity and producing anaesthesia. 



It is a matter of common experience ttiat the greater the amount of fatty 

 tissue in a subject undergoing anaesthetisation, the greater the amount of 

 anaesthetic required. The portion of anaesthetic which is absorbed by the 

 lipoid is imprisoned as far as purposes of anaesthetisation are concerned, and 

 so much the more anaesthetic must be given in order to raise the pressure of 

 anaesthetic sufficiently and cause combination between cell-protoplasm and 

 anaesthetic with resulting anaesthetisation. 



The ethereal extractives (lipoids) were obtained by the following method : — 

 The proteid of the serum or brain tissue was completely precipitated by 

 addition of excess of absolute alcohol, and the precipitate was separated from 

 the alcohol. The precipitate was thoroughly extracted with ether. The 

 absolute alcohol solution was evaporated to dryness and the residue also 

 thoroughly extracted with ether. The two ethereal extracts were united and 

 the ether evaporated off. The total ethereal extractive was weighed and then 

 made up into a fine emulsion by shaking with normal saline (G"75 per 

 cent.). The volume of the emulsion was made equal to that of the serum 

 originally taken, and in the case of the brain tissue the concentration of the 

 emulsion of the ethereal extract was made equal to the amount of lipoid 

 directly determined in the sheep's brain. For comparison with the results in 

 the case of the ethereal extractive emulsion of serum, the results in the case 

 of serum from our former paper are given, and the comparison is shown in 

 the two curves of fig. 3. In the case of the brain tissue and the emulsion of 

 the lipoids of brain tissue of equal concentration, the results are shown 

 alongside in the two curves of fig. 1. 



