1 9 o THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
lower concentrations by the low pressures of the anaesthetic as compared with 
solutions of equal strength in water or saline. 1 
Since both haemoglobin and, in a lesser degree, even clear serum contain a small 
percentage of lecithin and other bodies soluble in ether, it has been suggested to us 
that the results we have obtained may be due to the solubility of the anaesthetic in 
these bodies and not to an action upon the proteids, and that the experiments 
should be repeated with proteids which are entirely free from lipoids. 
In reply to this criticism, we would point out that in the first place it is a matter 
of great experimental difficulty, if not impossibility, to obtain proteids in solution 
unaltered and at the same time free from all trace of fat or lecithin ; and secondly, 
that a quantitative consideration of the conditions present in our experiments, as 
we shall proceed to demonstrate, makes it obvious that the small amount of lipoids 
present could not possibly account for the solubilities and absorption pressures 
which we have obtained. 
Taking first the question of the preparation of lipoid free proteids, any precipitation 
with a neutral saline reagent will throw down mechanically the lipoid as well as the 
proteid, and in any process of extraction with a solvent, such as ether, the proteid 
becomes gradually altered in its properties, as above described. In the preparation of 
crystallized haemoglobin, to ensure that no lecithin is also mechanically present, 
repeated re-crystallization becomes necessary, and, as a result, the properties, including 
the solubility, of the haemoglobin in water become rapidly modified. 
We have hence thought it better to obtain all our quantitative results with 
unattacked, unaltered proteid solutions, and the portion of our work dealing with 
the changes in physical properties of the solution, such as opalescence, turbidity, and, 
at higher concentrations, precipitation, 2 have left us in no doubt that the action is 
upon the dissolved proteid and not upon lipoids. 
A quantitative consideration of the conditions in the solutions experimented 
upon also makes it very clear that it is the proteids and not the lipoids which are 
responsible for the low pressures and high solubilities. 
The coefficient of distribution of chloroform between olive oil and water, 
according to Overton, is 30-33, and as those who support the lipoid theory use 
olive oil in their experiments as the representative of the lipoids, it would not be 
unfair to take as the basis of our calculations the above figure as the coefficient of 
distribution of the anaesthetic between the lipoids and water. Let us take, however, 
the higher figure of 40 as representing the coefficient of distribution for chloroform 
between the lipoids of the plasma and water, and calculate the percentage of lipoid 
which the plasma must contain in order that it may dissolve the amount of chloro- 
form which we have observed on the assumption that none is dissolved or attacked 
by the proteids. 
1. These experiments are in continuation, and the detailed results will appear in a subsequent paper. 
2. The large amount of chloroform in the precipitated proteid is clear evidence that the precipitation is due directly to a 
combination between the chloroform and the proteid. See Edie, p. 195. 
