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the respiratory muscles, and during this time the blood-pressure is falling—regularly and
gradually if the respiration is normal and not interfered with. The relaxation of the systemic
and respiratory muscles is due to narcosis, or sending to sleep, of the central nervous system,
and not to any direct action of chloroform upon the muscles themselves. After the muscles of
respiration are relaxed and respiration ceases, the heart can no longer obtain nourishment.
The animal then gradually dies, and the heart stops beating. The next point with regard to
this most interesting subject is that the work of the heart is not kept going either by a cardiac
centre in the brain or spinal cord, or by the ganglia in its own substance. At first this may
sound a little like heresy, but the tendency of modern physiology, and of modern physiologists
headed by Gaskell, is to show that the heart is a self-acting muscle, and a recent discovery by
Dr. Arthur Meigs of Pennsylvania gives ground for the belief that this conception is literally
true. The fibres of ordinary muscle derive their nutrition by absorption from delicate capillary
blood-vessels which run between them. Dr. Meigs has demonstrated that the muscular fibres of
the heart have a circulation peculiarly their own. He has shown that in the heart a
capillary blood-vessel enters into the substance of the muscle fibre, and there can be no doubt that each
fibre is nourished, and at the same time stimulated to action, by the blood flowing in its interior.
The muscular fibres of which the heart is composed are, if this view is correct, automatic hearts
in miniature, and the heart itself is thus a self-acting organ stimulated to rhythmic beating
throughout the whole of life by the very blood wihch nourishes it. Dr. Meigs's discovery
explains and accounts for the vigour of the circulation in the heart as well as the high state of
its nutrition. It also shows that each successive beat of the heart is produced by the beat
immediately preceding it. We have seen that the heart is independent of the central nervous
system, and there is no more ground for supposing that chloroform acts directly upon its
muscular tissue than that it acts directly upon any other muscular tissue. It is, therefore, a
fair inference that the heart can never be directly affected by chloroform. We now come to the
last link in the chain. Chloroform narcosis affects first the brain, and then the spinal cord.
The vaso-motor centre is situated in the upper part of the spinal cord, in the medulla oblongata,
and it must be narcotised like the other nerve centres. The vaso-motor muscles are thus
relaxed, and the blood-pressure falls. As the relaxation of the vaso-motor system is not vital,
the fall of blood-pressure is harmless."
Dr. Lawrie now handed round photographs of the tracings of the Hyderabad Commis-
sion's experiment No. 178. Ludwig II and Fick I, and of Experiment No. 186 of March 6th, 1890,
Ludwig I, II, III, and IV. Referring to the Ludwig tracing II of experiment No. 178, he said :
" In this observation chloroform administration was commenced at 2h. 51m. 40s. The
blood-pressure fell in the usual way, and at 2h. 54m. 35s. the breathing and heart both stopped.
A reading was taken on the Fick manometer, and the complete arrest of the heart's action for
over a minute is well shown at Fick 13. This reading is remarkable as showing that the
blood-pressure had already fallen as low as it could get before the heart stopped, and it did not
fall further after this happened. The fall must, therefore, have been due to vaso-motor
dilatation and not to weakening of the heart. I must now ask you to examine the
tracings of Experiment No. 186 of March 6th, 1890. Ludwig I shows the harmless effect of