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heart dilatation can really occur without fall of pressure, it must be a natural condition and
harmless. We have no right to expect the heart to do anything more than maintain pressure
in the aorta. That is its sole function, and if pressure be maintained the heart cannot be said
to fail. Professor Macwilliam' s description of rhythmical dilatation is also very suspicious. If
the dilatation were due to the chloroform action on the heart muscle it would assuredly go on
increasing to the end. Professor Macwilliam assumes dilatation to exist because his base line rises
whereas a rise of base line might be produced by anything that raised the heart as a whole.
The entire arrangement is so artificial that it is very difficult to accept any of his results, or to
believe that he can make all his levers and tambours, six in number, work in the perfect way
he describes, and at the same time that he can watch the condition of the pulmonary artery so
n a r r o wl y ( i n t h e c a t ! ) a s t o b e a b l e t o a s s e r t t h a t i t wa s s o f t a n d c o mp r e s s i b l e , a n d t h a t t h e
pressure within it was low. The fourth fact is meaningless. No one would expect the heart
to dilate with loss of blood. In bleeding, the blood is removed from the arteries and stored
outside the body. By chloroform poisoning blood is not lost, but is removed from the
arteries, the pressure falling in consequence, and stored in the veins, perhaps in the heart
itself. Granting, however, that Professor Macwilliam's cardiac dilatation is real, its depressing
influence is a pure assumption and is opposed to the very facts on which he relies to prove his
case.
The truth is that the Glasgow Committee in 1879, and Professor Macwilliam in 1890,
drew conclusions from an inadequate number of experiments. The Glasgow Committee made
their observations on less than half a dozen animals; Professor Macwilliam made his on 75 cats.
Just as the Hyderabad Commission and Professor Macwilliam have shown that the fall of
pressure, which the Glasgow Committee considered dangerous in chloroform administration, is
harmless, and may be a safeguard, so some future observer will show that Professor Macwilliam's
cardiac dilatation is not only harmless but is a safeguard also. It would not be surprising if
Professor Macwilliam's dilatation of the heart turns out in this way to be an important
physiological discovery of the same kind as Dr. Bomford' s discovery of the safeguard action of
the vagus nerve. It is likely enough that the whole vascular system is relaxed by chloroform,
i ncl udi ng t he wal l s of t he hear t . Under such ci r cumst ances t he saf eguar d act i on of di l at at i on
may consist in an arrangement to allow the blood naturally to collect in the heart, which is
the best place for it, ready to be pumped into the aorta at a moment's notice, and so restore the
pressure. Suppose the heart is completely relaxed by chloroform, as the systemic muscles are,
it will go on again if respiration is kept up. In any case there is no danger clinically from
cardi ac di l at at i on i n chl oroform i nhal at i on. Cl i ni cal resul t s cannot be accept ed onl y when t hey
favour the view that chloroform is dangerous. Probably as much chloroform is used in India
as in the whole of Europe, and we have no evidence of dilatation of the heart, as a dangerous
effect of chloroform, from one end of the year to the other.
The Hyderabad Commission did not discover the key to the safe administration of chlo
-roform, until they had made observations upon 565 animals and had reached their 148th mano-
meter experiment. The tracings of this experiment are produced here, and ought to be com-
pared with the tracings of the experiment of March 6th, 1890, which were so beautifully engraved
in the January number of the Medical Chronicle. In experiment No. 148 chloroform was at