LABORATORY MANUAL OF PHYSIOLOGY. 



Note also every few seconds the condition of the various re- 

 flexes. Among these try the reaction of the pupil to light, the con- 

 junctival reflex, the reflex upon tickling the nares, and cutaneous 

 reflexes. Note the time at which each one of these reflexes disap- 

 pears. Note time when struggling begins. How do these respira- 

 tory phenomena differ from, and resemble, those of asphyxia ? 



VIII. RESPIRATORY CENTRE. 



Narcotize a rabbit lightly with morphine. Anaesthetize with 

 ether. Expose the trachea and both carotid arteries through a 

 median cervical incision. Introduce a cannula into the trachea 

 and tie both carotids. 



Change the position of the animal so that it lies on the rabbit- 

 board belly down. Make an incision in the median line through 

 the integument of the skull from the root of the nose to the occiput. 

 Pull the skin flaps to one side, exposing the parietal bones of the 

 skull. Make two trephine openings, one through the parietal bone 

 of each side, enlarging the openings with cutting forceps, until the 

 entire skull cap is removed. Be careful in crossing the median 

 line not to injure the longitudinal venous sinus. 



1 . Open and lay back the dura on each side, thus exposing both 

 cerebral hemispheres. With a blunt spade or scalpel handle 

 crush both cerebral lobes. Control the hemorrhage by packing 

 with cotton moistened with adrenalin i to 10,000, or use the actual 

 cautery. 



Observe the respiratory movements before, during, and after 

 this operation. Do respirations continue after the removal of the 

 cerebrum? Is the controlling respiratory centre located, there- 

 fore, in the excised portion of brain ? 



2. Continue the median dorsal incision until all the cervical ver- 

 tebrae are exposed. Continue the removal of the skull cap until 

 the cerebellar hemispheres are exposed. Remove the cerebellar 

 hemispheres in the same way that the cerebral lobes were re- 

 moved. 



Do the respiratory movements cease in the absence of the cere- 



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