OF TEMPERATURE UPON THE BEAT OF THE DOG’S HEART. 
669 
vessel E. This is prevented by the collar a, which fits round the neck of the flask, 
and is attached by the bars b, b, to the upper edge of E. 
In connexion with C are shown the tubes which pass through the air-tight cork of 
each Mabiotte’s flask. These are four in number. Two (c, cl) are used when the 
flask is to be filled with blood; the other two (e,f) are employed when the flask 
is at work supplying the heart. When C is to be filled, the tubes e and f are closed 
by clamps or stopcocks put on the pieces of rubber tubing attached to their upper 
ends. The clamp g on the rubber tube attached to the upper end of d (which tubing, 
as shown in the figure, passes through an aperture, G, in the roof of the chamber) is 
opened, as is also the stopcock h, which is placed on the course of the tube leading from 
c to the funnel F. Meanwhile the corresponding stopcock li , on the tube leading to 
the flask D, is closed. Defibrinated blood poured into F then enters the flask C 
through c, and the air which it displaces is driven out through d. C having been 
four-fifths filled, the stopcock li and the clamp g are closed, and the clamp i opened. 
From the tube f, which dips deepest into the flask C, leads the rubber tube k ; this 
passes through the end B of the warm chamber, and the next part of its course is 
shown in Plate 48, fig. 2, where k is seen to lead to the stopcock l, which is connected 
with one limb of the y-piece m, another limb of which is attached to the corresponding 
tube k', leading from the flask D. The remaining limb of the Y-piece leads to the 
rubber tube n, which is seen again in fig. 1, after entering the warm chamber. 
There n is seen to be continuous with the ~f-piece o, in the vertical limb of which is 
the thermometer p. Beyond the T-piece is the stopcock q, which ends in the rubber 
tubing y. 
The flask C having been filled, we next go to the flask D, in connexion with which 
much of the details of the tubing have been omitted; but in all respects the flasks C 
and D and their connexions are similar. In the lettering of. the figures whenever a 
connexion of C is indicated by a letter, the corresponding connexion of D is indicated 
by the same letter with a dash : h of C answers to ti of D ; d of C to cl' of D ; i of C 
to % of D, and so forth; so that a detailed description of the tubes connected with D 
is unnecessary. 
To fill D the stopcock h is closed, and h' opened, as is also g', while i' and k' are 
closed. Defibrinated blood poured into F then enters the flask D, and is added until 
that flask is about one-fourth filled. Then the stopcock h' is closed, the clamp g' 
screwed up, and the clamp % opened. The further course of k' is seen in Plate 48, 
fig. 2, where it is shown as joining k at m; it therefore ends also in the stopcock and 
rubber tubing q and y. 
So far we have got the flask C four-fifths full of defibrinated blood and the flask D 
one-fourth full. It remains to fill the tube f and its fellow, and the system of tubes 
leading from both of them to the stopcock q, which during an experiment is connected 
with the superior vena cava, and has to supply the heart steadily with defibrinated 
blood. The tube f and its fellow have to act as syphons, and therefore the lower ends 
mbccclxxxiii. 4 n 
