i6o THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
leaving; others free, while another anaesthetic or alkaloid will form combinations in 
a different type of cell and so produce a different physiological effect. 
Considered from this point of view, the basic anaesthetics which (as shown by 
the greater slowness with which their effect disappears) form more stable compounds 
will be more specific in their action, while the indifferent anaesthetics or, as they 
might perhaps better be called, general anaesthetics such as ether and chloroform, which 
form much more loose combinations, probably of a physical character with the 
proteid of the protoplasm, will be adapted for more general combination, and will 
affect all cells more equally, although even here, as has already been pointed out, 
there is selective action in lessened degree. 
We may now pass from the history of the subject to a description of our 
own experiments, which have chiefly been made with chloroform, although certain 
experiments have been added with other anaesthetics, which show that the conclusions 
deduced from the experiments with chloroform hold also for other anaesthetics, and 
at the outset we desire to acknowledge that our attention was first attracted to the 
subject by witnessing the experiments of Sherrington and Sowton 1 upon the effects 
of chloroform on the excised mammalian heart, fed by a current of Ringer's or 
Locke's solution, and through which, later, a similar current, but containing in 
addition small amounts of chloroform, could be perfused. 
These authors observed that a concentration of chloroform in the Locke solu- 
tion, amounting to only i in 100,000, produced a marked and unfailing action in 
diminishing the extent of the cardiac contractions, and, further, that this effect appeared 
rapidly after the dilute chloroform solution reached the heart, lasted just as long as the 
chloroform in this excessively low but yet adequate concentration was passed 
through, and ceased almost immediately as soon as the normal Locke's solution was 
recurred to, the heart attaining again its normal force. 
This effect could be repeated as often as was desired, and there was no cumula- 
tive action whatever, that is, no matter how prolonged the passage of the chloroform 
solution on passing back to the normal Locke's solution, the chloroform effect 
rapily disappeared, and again recovered when the chloroform was once more turned 
on. 
It was this latter effect which suggested the experiments on the chemistry of 
anaesthesia recorded in this paper. It was quite obvious that the effect of the 
chloroform upon the cardiac muscle fibres depended solely upon the concentration 
(solution tension or osmotic pressure) of the chloroform in the cell for the time 
being, and not at all upon the total amount of chloroform which had been fed to the 
heart up to the moment of observation. 
This experimental fact suggested the view that the effect upon the cell was due 
to some combination being formed between the protoplasm and the chloroform, and 
I. Thompson Tales and Johnston Laboratories Report, Vol. 5, Part I, p. 69. 
