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I have stated (vide The Lancet for June 21st, 1890), and still state that a probable
cause of cardiac dilatation, when chloroform is pumped into the lungs with bellows, is
pulmonary stasis. This statement is made on the authority of the greatest physiologists in
the world—Professors Michael Foster and Gaskell. In 1879 the Glasgow Committee attributed
cardiac dilatation to pulmonary obstruction; in 1890 they ascribed it to paralysis of the
heart; and now Professor Macwilliam asserts that it must result from a depressing influence
exerted directly by the anæsthetic on the heart, presumably as a muscle. It is remarkable
that while the Glasgow Committee and Professor Wood are as much opposed to Professor
Macwilliam as we are, they are all three antagonistic to the Hyderabad Commission, but they
are only linked by unenlightened fear of chloroform.
The profound and irreconcilable differences of opinion beween the Glasgow Committee
in 1879 and in 1890, and between the Glasgow Committee and Professor Macwilliam, are of no
importance in this connection, as there are serious sources of error in Professor Macwilliam's
experiments and conclusions, which reduce all his arguments about dilatation of the heart to
insignificance.
Professor Macwilliam gives four facts, which he says, prove conclusively that cardiac
dilatation is not due to fall of blood-pressure. They are as follows:—
"(1) Dilatation of the heart does not by any means always run parallel to the fall of
pressure which ordinarily results from the administration of chloroform. Sometimes there is
a very marked fall of pressure, with little or no dilatation of the heart; while at others the
heart begins to dilate before the pressure begins to fall. (2) Moreover, the heart in some
instances begins to dilate during the temporary rise of pressure which at times precedes the
fall. (3) Further, there may be a distinct dilatation of the heart without any change of
pressure at all. (4) Lastly, it can easily be shown that a simple fall of pressure, equal in
amount to that which ordinarily occurs under chloroform, induced by means which do not
directly affect the heart (e.g., section of a vaso motor nerve, hæmorrhage, &c.) does not cause
dilatation of the organ as chloroform does."
These four facts, if facts they be, distinctly prove that Professor Macwilliam's results
with chloroform are not uniform. Sometimes one effect is produced, sometimes another. I
shall demonstrate later that the irregularity of his results was caused by the irregularity
of, or interference with, the respiration and the normal oxygenation of the blood in his
experiments.
From Professor Macwilliam's first fact it is clear that dilatation is not failure of the
heart function, because it bears no relation to the blood-pressure. Fact two shows that dilata
-tion is probably the result of the rising pressure with which it occurs, and this in its turn is
the result of the contraction of the small arteries stopping the outflow of blood. Professor
Macwilliam's third fact, that "there may be a distinct dilatation of the heart without any
change of pressure at all" is paradoxical. It is impossible to believe that blood-pressure can
be maintained with a failing heart, seeing that the heart is the only source of pressure. If