254 C. J. MARTIN. 
enfeeblement of the circulation would also operate in the same — 
manner, a simultaneous record of the blood pressure was taken in — 
order to keep a check on this possible source of error. 
Rabbits of about 1} kilogrammes in weight were used. The 
carotid artery was connected with a mercury manometer, anda — 
glass cannula tied into the trachea, The glass cannula communi — 
cated with a Marey’s tambour, the artificial respiration apparatus, 
and the external air by three taps. By means of the tap connected — 
with the respiration apparatus, artificial inflation could be iy 
on or off at a moment’s notice. The lever of the tambour and : 
float with scribe on the mercury manometer registered ona travel: 
ling surface, the respiratory movements and the blood pressure 
respectively. The left phrenic nerve was dissected out inthe — 
- neck, and placed upon electrodes. The nerve was prevented from s 
drying by being, together with the electrodes, again covered with 
the skin. The phrenic was stimulated by the induced current : 
from the secondary terminals of a Du Bois Reymond’s coil, : 
and the primary circuit was broken by the same arrangement, a 
was used in the experiments with frogs, described above. In the ] 
primary circuit was a Daniel cell. At the commencement da 
each experiment a record of the respiration, blood pressure, and 
the greatest distance between the coils of the inductorium vie 
a contraction of the diaphragm followed stimulation of the phrenle, 
was obtained. It was not found necessary to open the abdomen 
and observe the diaphragm directly, as when a contraction of : 
left half of the diaphragm occurred, there was an unmistakeable 
sharp movement of the fur on that side, owing to the ue 
retraction of the lower ribs. The same series of observations 
were made every fifteen minutes after the injection of the eae 
and as soon as the respiration exhibited any signs of filet 
artificial inflation was brought into action by turning the 2 
connected with the respiration pump. ‘The animal’s : 
to breathe by itself was recorded every fifteen minutes by lei 
off the artificial respiration for a few seconds. In the tabula’ 
account of experiments I have employed the extent of the resp 
FT, Cone tl as SE NT nie Vee eR aes 5 a TA ¥ 
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putes 
