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sion of this sort as a result of the administration of ether. Indeed, in more than one
instance when the periodic depression was strongly marked and kept recurring again and again,
a dose of ether was speedily followed by a complete disappearance of the phenomenon in ques
- t i o n . T h e h e a r t ' s a c t i o n i m p r o v e d i n a r e m a r k a b l e w a y ; i t b e c a m e s t r o n g , s t e a d y a n d r e g u l a r .
It may be noted that the occurrence of this great depression of the cardiac action in cats
some time after the administration of chloroform, and after partial recovery from its effects,
has a curious parallel in the records of some cases in the human subject.
Effect of Ether compared with those of Chloroform.
—
The results obtained with ether
have been strikingly different from those following the use of chloroform The ether was
administered in the same way as chloroform--by injection into the anæsthetic bottle—but
larger quantities were used (for example, 25 minims at a time), and the dose was
less gradually given. Instead of being gradually introduced drop by drop into the
bottle, it was very often thrown quickly in from the syringe. The condition of the con
-junctival reflex was closely watched. Often the dose was given at a time when unconscious
winking on touching the conjuctiva was distinctly marked. Then a sufficiency of ether was
given to cause a complete abolition on reflex. The blood-pressure unusually fell to some extent, but the cardiac condition was very different from that seen under chloroform. Instead
of becoming markedly dilated as with chloroform, the heart showed, as a rule, no dilatation
or there was very slight and transient dilatation lasting only a few seconds, attaining no
serious preportions, and Speedily passing away. The occurrence of even a brief and
fleeting phase of slight dilatation was chiefly associated with those experiments where
ether was given in large amount with great suddenness. In very many instances
there was not the slightest indication of cardiac dilatations. On the contrary, a change in
the opposite direction was on several occasions observed—a rapid recovery from the attacks
of periodic ventricular depression that have been described as sometimes following doses of
chloroform. The difference between chloroform and ether in their relation to cardiac dilatation
is strikingly illustrated in the tracings obtained in the way I have already described. Again
and again in the course of a prolonged experiment the conjunctival reflex was abolished by
the use of ether without any special effect upon the heart, whereas in the same chloro
-form, administered in the same way brought about a marked dilatation of the cardiac chambers
—
when given gradually, mixed with abundance of air, in an amount sufficient to abolish the con
-junctival reflex, and indeed often before that point had been reached. In some experiments
the anæsthetics were alternately given, and the characteristic results of the two were alternately
manifested with great constancy and precision. Chloroform (always under 4 per cent. of
chloroform vapour in the air) was given, leading to partial or complete loss of the conjunctival
reflex and pronounced dilatation of the heart. When these effects had passed away and the
original condition had been restored, ether was given in such an amount as to abolish the con
-junctival reflex; this was usually attended by no cardiac dilatation. When the effects of
ether had disappeared, chloroform was given with the same results as before; then ether again
with its characteristic difference of effect, and so on.
When ether is given with the result of causing a fall of blood-pressure, there is at
the same time a reduction in the force of the heart's beat. This reduction appears, as a rule,