303
ment of other modes of registration, for example, by the use of light lovers resting on the
auricle and ventricle and inscribing their movements directly (without the intervention of
tambours) upon the smoked paper. There has been a complete agreement in all important
points between the results obtained by the different methods.
It may here be remarked that the amount of mechanical interference involved in the
application of the above method does not cause any serious injury to the state of the heart and
the vascular system generally. The heart goes on beating with remarkable regularity and
steadiness for many hours; a high blood-pressure is maintained, and the circulation is carried
on with great activity.
The rate of the movements of artificial respiration is usually indicated in the auricular
tracings by a slight rhythmical oscillation in the base line of the taaeing. A time record
(seconds) is inscribed on the same paper alongside of the other tracings: and, in addition,
electrical signal marked the points of time at Which vauious events (giving of chloroform, &c.)
occurred.
Long sheets of smoked paper were employed, and upon them there was Obtained side by
side, by the method described, a simultaneous record of (1) the arterial bblood-pressure, (2) the
action of the right or left auricle, (3) the action of the right or left ventricle, (4) the number
of the artificial respiratory movements, (5) a time trace marking seconds, and (6) the inscrip--
tion of an electrical signal indicating the time of occurrence of certain events.
M o d e o f A d m i n i s t e r i n g t h e A n æ s t h e t i c . — T h ebellows employed for artificial respiration
were connected with the canula in the animal's trachea chiefly by India-rubber tubing. In
the course of this tubing a wide-mouthed bottle was interposed, so that the air coming from the
bellows passed through the bottle. The tube leading from the bellows was attached to a glass
tube which passed through the cork and reached down to within one-eighth of an inch of the
bottom of the bottle. The air entering the bottle through this tube passed out by another tube
winch projected just beyond the surface of the cork internally, and was connected outside the
bottle with a piece of India-rubber tubing leading to the tracheal canula. Between the bottle and
h e t r a c h e a l c a n u l a w e r e t w o s i d e t u b e s t h r o u g h w h i c h a v e r y l a r g e p a r t o f t h e a i r s e n t b y t h e
bellows through the bottle escaped, so that only a small part of the air that passed through the
bot t l e ent ered t he ani mal ' s l ungs. Through t hese si de t ubes t he ai r sent out from t he l ungs
in expiration also escaped.
The anæsthetic to be administered was mixed with the air as it passed through the bottle,
This was done by putting the chloroform or ether into a hypodermic syringe, the needle of
which was made to pass through the cork: the anæsthetic was then, by means of the syringe,
thrown into the bottle in the amount desired. In the case of chloroform, small quantities were
used commonly one minim at a time. This amount usually required about twelve (artificial)
respiratory movements to evaporate it, and, as each movement of the bellows sent fully 4.54
cubic inches of air through the bottle, it is evident that the relative amounts of chloroform and
air were 1 minim of chloroform in about 54.5 cubic inches of air. Now as 1 minim of chlo-
roform, when evaporated, gives only a fraction over 1 cubic inch of vapour, it is clear that the
strength of chloroform vapour in the air was about 2 per cent. No doubt, however, the evapo-