295
piration. Dogs always ceased to respire while the heart continued to beat, as also did rabbits to
which diluted vapour had been given, and the majority of these could be revived. The reflexes
appear to behave in the same way as in chloroform narcosis. Ether was borne in higher con
- c e n t r a t i o n t h a n c h l o r o f o r m , a n d t h e r e s p i r a t i o n c o u l d b e m o r e c e r t a i n l y r e s t o r e d . F o r
example, in one case 8 per cent, was given for two hours without killing the animal, while
with chloroform 5 per cent. was fatal after one hour and a-half. This fact is the more
striking because a very much larger quantity of ether than of chloroform is given in a
concentration of 8 per cent. Theoretically, 2·7 times as much ether as chloroform should
be carried to the lungs by a given quantity of air, and by actual experiment I found a
proportion of 2·61: 1. In both anæsthetics the action on heart and respiration seems the
same, a difference in degree only being perceptible. Ether can be given in greater
with safety: but so long as the p r o p o r t i o n o f d r u g t o a i r i s k e p t l o w e n o u g h
either can be used with safety. The concentration necessary to keep rabbits and dogs
"under" chloroform is respectively four and eight parts chloroform vapour (at from 15° to
17° C.) to ninety-six and ninety-two parts pure air. Since, however, the concentration
necessary to maintain narcosis varied in different species of animals, no inference could be made
as to that necessary for men, and my results would have been incomplete had I not been
enabled through the kindness of Professor Girard and Dr. Niehans to earry out some experi-
ments in their operating threatre in Bern Inselspital. In these experiments the anæsthetic
was given in the same way
as in my experiments on animals, with the exception that, instead
of a tracheal canula, a Y-shaped glass tube was used, the two ends fitting tightly into the
patient's nostrils. Expiration was allowed through the mouth, but inspiration through it was
prevented by a valved respirator. The patients in general did not object to the method, and
one who had to be anæsthetised again some days subsequently begged that the apparatus might
be used again instead of the mask. Narcosis was attained in from five to twelve minutes by
a mixture of 15 or 20 per cent. of chloroform, and could be kept up by continued inhalation
of to 7 per cent, in children and of 7 to 10 per cent, in adults. Almost no excitement occur
-red. Throughout the narcosis the face and conjunctiva remained red, and in several cases the
concentration necessary to keep up insensibility with retention of the corneal reflex was main
-tained. With ether adults were nareotised with difficulty, and only after prolonged inhalation.
Anæsthesia was afterwards kept up by a concentration of 10 to 15 per cent. Children pre
-sented less difficulty, requiring 25 to 30 per cent. to induce insensibility, which continued
uninterrupted with a concentration of 10 to 15 per cent. In all cases the usual increased
secretion of tears, saliva, and mueus was manifested. The difficulty in inducing narcosis with
ether seems to confirm the theory of many observers that ether alone is insufficient for this
purpose, and must be aided by a partial asphyxia.
The results of these narcoses may be summed up shortly by saying that, to maintain
narcosis with chloroform, a concentration of five to seven and seven to ten parts of chloroform
saturated to ninety and ninety-five parts pure air must be adopted for children and adults
respectively; while if ether be used, a concentration of ten to fifteen parts saturated to ninety
and eighty-five parts pure air is suitable for all ages. The drug may be inhaled in a slightly
higher concentration to induce narcosis, but, as soon as the eyelid reflex disappears, the above