586 
DR. SANDERSON ON THE INFLUENCE EXERCISED BA THE 
tested by observing the results obtained when a mode of breathing is induced in which 
the mechanism is reversed or altered while the chemical changes are the same. For 
this purpose I have availed myself of the well-known properties of woorara, under the 
influence of which the respiratory movements cease, while those of the heart remain 
unaltered. 
3. Experiments as to the relation between the arterial pressure and the thoracic 
movements in artificial respiration. 
Observations XIII. -XVI. — August 11th and 16th, ] 865, and June 2nd and 8th, 1866’ 
(Plates XXIV. & XXV.). 
The animals employed on these occasions were (1) a short-legged spotted cur, (2) a 
small English terrier, (3) a bull terrier weighing 13 lbs., (4) a black and tan terrier 
weighing 18^ lbs. All were males. With the exception that in the last experiment 
the pneumogastric nerves were divided, the procedure was the same in each case. The 
rates of movement of the paper were as follows: — August 11th, 1 inch in 3'2 seconds; 
August 16th, 1 inch in 3'5 seconds; June 2nd and 8th, 1 inch in 2 - 8 seconds. The 
solution of woorara employed in 1865 was kindly given by Professor Harley; that used 
in 1866 was obtained some years ago from Professor Pelouze, and is believed to have 
been derived from the same source as that used by Bernard in his investigations of the 
toxic properties of woorara. The solution contains 0-01 gramme of the substance in 
each cubic centimetre. The solution was always injected into the subcutaneous cellular 
tissue. In the two more recent experiments the quantity used corresponded to one- 
tenth of a gramme of solid woorara. The respiratory movements ceased at periods 
varying from twelve to fifteen minutes after the injection. 
The apparatus was modified so as to admit of artificial respiration. For this purpose 
a common pair of bellows was employed, which could be adapted at will to the open 
end of the T tube. The caoutchouc bag was provided with a second tube of the same 
size as that by which it was connected with the T tube. This additional tube was kept 
closed so long as the animal continued to respire naturally. As soon as it was desired 
to practise artifical respiration, air was injected by the bellows ; of this air a sufficient 
proportion inflated the chest, while the remainder passed out through the caoutchouc 
bag. Immediately after each stroke of the bellows the air introduced was expelled by 
the elastic reaction of the thoracic walls. By this arrangement the too forcible inflation 
of the lungs was effectually prevented, and the complete removal of breathed ah from 
the apparatus was ensured. As the experiments were all of the same nature, I prefer to 
enumerate the results obtained rather in their relation to each other than in the order 
of time. 
1. Under certain circumstances, and particularly when artificial respiration is practised 
at long intervals, the inflation of the lungs appears to produce analogous effects to those 
of ordinary breathing. This was well seen during the observations made on the 16th 
