974. REPORT—1896. 
5. On the Different Forms of the Respiration in Man. 
By W. Marcet, .D., LBS. 
The different forms may be thus stated :—- 
1. Normal, automatic (unconscious) breathing. 
2. Forced breathing 
8. Breathing in exercise. 
4, Breathing under the influence of a strong effort of volition. 
Forced breathing.—If a succession of deep inspirations be taken, the tracing 
rises much more steeply than normal, a pause (apnoea) follows, and then breathing 
returns increased beyond normal, after which the line returns parallel to normal. 
Forced breathing includes sneezing, and sighing, and yawning. 
Exercise breathing.—In exercise such as stepping, the line rises more steeply 
than normal, there is no pause or cessation of exercise, but the line continues 
steeper than normal for some time and gradually returns parallel to normal. 
Volition breathing.—If the volition be exercised strongly towards muscular 
work of some kind, though with the musclesat rest, the volume of the air inspired is 
increased beyond the normal. On dropping the effort of volition a respiratory pause 
follows, and then increased breathing and gradual return to normal, the tracing 
taking much the same direction as in forced breathing. If, however, the volition 
be directed towards the respiration there is no pause, but the line returns parallel to 
normal almost directly. Volition for any kind of muscular exercise produces the 
pause, but when the attention is directed towards the respiration there is no 
apnoea. 
; Even when exercise such as stepping or gyrating the arms is taken, when the 
volition is exerted as strongly as possible towards the exercise,on dropping the 
effort of volition, even though the exercise be continued, the pause is still strongly 
marked. 
The only possible explanation of the occurrence of the pause is that when the 
attention is directed towards the respiration only one brain centre is concerned, 
and hence when the effort of volition is dropped no time is lost before the centre 
of respiration asserts itself; whereas when the volition is exerted towards some 
form of exercise, two brain centres are concerned, and on dropping the effort of 
volition, some time (a few seconds) is lost before the centre of respiration has 
shaken off the influence of the centre of locomotion; and it is to this that the 
pause must be due, and not any excess of oxygen in the blood, as the automatic 
respiration of 50 per cent. oxygen produces no pause. 
FRIDAY, SEPTEMBER 18. 
The following Papers were read :— 
1. The Occurrence of Lever in Mice. 
By Professor J. Lorrain Suiru, IA., ILD., Queen’s College, Belfast, 
and F. F. Wesproox, JZ.D., Minneapolis, U.S.A. 
Krehl’s investigation on the production of fever in various species of animals 
has proved that a great difference exists in the extent to which some of the smaller 
mammals react to fever-producing substances. It is comparatively easy, he found, 
to produce fever in rabbits. Guinea-pigs and dogs were more resistent, and in the 
case of the hedgehog it was impossible, so far as his research was carried, to pro- 
duce the condition at all. Similar results were obtained with pigeons and chickens. 
The present research attempts to discover whether in the case of mice the same 
difficulty in the production of fever exists; and, if so, whether thereis at the same 
me an absence of the changes in metabolism which in other animals accompany 
ever. 
