110 
ON CHLOROFORM. 
operations. In the second degree mental functions may be exer- 
cised and voluntary actions performed, but in a disordered manner; 
the movements are instinctive, guided by volition, though not by 
knowledge or reason; there may be struggling, screaming, or 
laughing ; the patient may be tractable or obstinate ; dreams occur 
in this stage. An operation would cause pain, though the patient 
might, perhapo, not remember it : this stage is not proper for ope- 
rations. In the third degree there is no evidence of any mental 
function being exercised, and, consequently, no voluntary motions 
occur ; but muscular contractions, in addition to those concerned in 
respiration, may sometimes take place as the effect of the ether, or 
of external impression. The eyes are stationary, the breathing is 
usually regular and deep, though it sometimes stops for a time, 
and there may be muscular rigidity : in operations there may be 
some flinching and moaning, but no articulate sound, and there is 
no recollection cf what has been done. In the fourth degree no 
movements are seen except those of respiration, and patients are 
incapable of being influenced by external impressions. The eye- 
lids fall, the eyes are fixed, the muscles are all relaxed, the face is 
placid and expressionless, the breathing regular and automatic, and 
sometimes there is snoring, a state which would be alarming if we 
did not know the cause of it. In this the patient remains perfectly 
passive under every kind of operation. In the fifth degree, not 
witnessed in the human being, the respiratory movements are more 
or less paralyzed, and become difficult, feeble, and irregular. If 
continued, this ends in death; yet, according to Dr. Snow, the 
animals always recover if the vapour is discontinued before the 
breathing has actually ceased. 
These various stages disappear in the inverse order in which 
they make their appearance ; that is, the third succeeds the fourth, 
the second succeeds the third, and the first concludes. It is to be 
observed that the degree of insensibility is greater in a stage when 
retiring than when advancing ; that is, for instance, a patient might 
feel, while in the second stage during its advance to the third, 
what he would net feel in the same stage during its retiring from 
the third. 
The proper stages for operations .are, according to Dr. Snow, the 
third or fourth ; the latter, if there be any muscular movement or 
rigidity in the third stage. If there is the least snoring, the opera- 
tion maybe commenced, and the ether should be temporarily with- 
drawn till the snoring ceases. The insensibility may be kept up 
for a long time without risk, by allowing partial recovery occasion- 
ally, by withdrawing the inhaled agent for a time. 
Dr. Simpson points out the following conditions as necessary to 
be attended to in producing anesthesia : — 1st, perfect quiet and 
