84 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
when offered to it at a certain solution (osmotic) pressure. Thus, in our experiments, 
the beat of Heart 8 was reduced by 92 per cent, by administration to it of 1*4 milli- 
grammes of CHC1, offered to it as a -003 per cent, solution (in Ringer's fluid), that is, 
under a solution pressure (assuming CHC1 ; to be a perfect monomolecular gas) of 
4*79 mm. Hg., at temperature 37° C. Stated in amounts calculated per gramme 
of heart tissue (Heart 8 weighs 12*19 grammes), o - 1 14 milligrammes per gramme 
cardiac tissue offered under that pressure practically annulled the heart's action. In 
other words, about 300 cub. cent, of a 2 per cent, admixture of chloroform with air 
administered to an adult man, if its chloroform all reached the heart, and reached it 
under the above solution pressure, would, for the time being, practically annul cardiac 
action. 
The above figure is given because it may serve to indicate the sensitiveness 
of the mammalian heart to chloroform. The practical problem requires many more 
data than we possess at present before it can be completely dealt with. Of chloro- 
form inhaled, what portion enters the coronary blood-vessels ? What tension of 
chloroform in air inhaled will, through the pulmonary membrane, charge the blood 
so as to give therein an osmotic pressure of 5 - oi mm. Hg., as in a Ringer's fluid 
containing 30 mgrms. CHC1, per litre ? From Mr. Vernon Harcourt's data, 
furnished in last year's Report of the Committee* (Appendices, paper II, pp. 15, 16), 
chloroform in such a dilution in water at 37 0 C. would have a vapour tension of 
•55 mm. Hg. In the modified Ringer's solution we have used for perfusion, it 
may be supposed that the tension would not be appreciably different from that in 
water. But the tension of chloroform or any dilution with blood is certainly 
less — probably far less — than for the same dilution with Ringer's fluid. The 
experiments of Pohl, Harcourt, and Wells all indicate this. If the physiological 
activity of the chloroform is graded by its solution (osmotic) pressure, as we infer it 
is, observations easily made indicate that for the same dilution that pressure is much 
lower in blood than in Ringer's fluid. We find, for instance, tadpoles much more 
speedily paralysed by chloroform exhibited in Ringer's fluid than in blood. 
Our observations were carried out as follows: — Into two similar shallow glass dishes, provided with 
glass covers, equal quantities of equal dilutions of CHC1 3 in Ringer and in defibrinated blood (pig), 
respectively, are placed — the CHC1 3 in ' Ringer ' into one vessel, that in blood into the other. Two 
tadpoles are chosen similar in size and development. One (A) is placed in the one vessel, the other (B) 
in the other. Both A and B swim about freely, and gradually show signs of decreasing vigour and 
activity. The time taken for A and B respectively to become motionless and irresponsive when touched 
is noted. The chloroformed animal is, as soon as paralysed, at once removed to fresh water ; the time 
is then noted which is required for it to regain its motility. Both animals having been allowed to 
recover perfectly in the fresh water, both are then again put into the chloroform containing fluids, but A 
now into the fluid previously occupied by B, and vice versa. The times of anaesthetization and 
subsequent recover}- are then again observed for both A and B. The following are examples of such 
times : — 
* British Medical Journal, July 12, 1902 
