jo THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
same pressure. Three 3-way taps in the Y-shaped tube allowed perfect control and 
interchange of the feeding fluids without any intermission of the supply to the heart. 
The capacity of the tubing between the CHCl r solution inlet and the heart was 5 
cub. cent. The point marked on the graphic records by the CHC1, signal as the 
moment of commencement of admission of CHClj solution to the heart is the 
moment at which this tap (2, Fig. 1) was turned, admitting the CHC1; solution to 
the delivery tube just above the aorta. The real moment of admission of the CHC1 ; 
solution to the heart was therefore a little later than that marked, beginning actually 
after the intervening 5 cub. cent, of unchloroformed fluid had passed into the heart. 
The rate of flow of fluid through the hearts employed was usually about 1 cub. cent, 
per second, the lost time therefore between the turning of the CHC1 3 tap and the 
real entrance of the CHC1, solution into the heart was therefore usually about five 
seconds. 
Disposition of apparatus. 0 2 , cylinder containing compressed oxygen. A, 1 o-litre flask containing 
modified Ringer's solution ; B, 2-litre flask containing the modified Ringer's solution in which a known 
quantity of chloroform is dissolved ; C, bottle preventing reflux of fluid into gas tap, etc. ; D, bottle con- 
taining same chloroform solution as B ; E, thermometer in the water-bath W ; F, manometer, showing 
pressure of delivery oi the solutions given to the aorta of the heart H ; I, 2, 3, three 3-way taps ; 
4. 5, clamps ; An, auricular recording lever ; Ye, ventricular recording lever ; X, diffuse pole of the 
unipolar faradization apparatus applied to the clamped tissue of the root of the lung ; G, standard support- 
ing the clamps which fix the isolated heart. The CHC13 signal records the moment of opening or closing 
oi tap 2. 
The contractions of the heart were recorded by attaching light writing levers 
to the auricle and ventricle, respectively. The threads were fixed to the heart by 
minute hooks made from the thin pins used by entomologists for pinning out small 
insects. The threads were in part of their length made of very narrow strips of 
thinnest gutta-percha sheet. This was found especially necessary for the auricular 
writing lever, the movement of contraction of the auricle being so quick as to other- 
wise lead to much deformation of the trace by the inertia of the lever. The levers 
