LABORATORY MANUAL OF PHYSIOLOGY. 



Secure the cervical sympathetic nerve on one side with two liga- 

 tures. Cut the nerve between the ligatures. After a short time, 

 again compare the two ears. Is there any change in vascularity of 

 the ear of the side upon which the nerve was cut as compared with 

 the ear of the sound side ? 



While observing the two ears, stimulate the peripheral end of 

 the cut nerve. What change occurs in the blood supply to the ear 

 of the stimulated side? Note any other phenomena which occur 

 during stimulation of the cervical sympathetic nerve. What is the 

 function of the nerve as far as the vascular supply to the ear is con- 

 cerned ? How does the temperature of the ear on the operated side 

 compare with that of the ear on the sound side ? 



Locate the cardiac impulse on the chest wall of the rabbit and 

 introduce into the heart a fine knitting-needle. This will move 

 with the heart-beat and serve as an indicator. Place a bit of ab- 

 sorbent cotton saturated with chloroform over the end of the tra- 

 cheal cannula. Note the effect on the heart-beat. Kill the animal 

 w r ith chloroform. Note which stops first, heart-beat or respiration. 

 After the respirations and excursions of the heart needle have both 

 stopped, open the thorax and observe whether or not the heart is 

 still feebly beating. 



6. Effect of Hemorrhage on Blood Pressure. Prepare a 

 rabbit, as before, for a blood-pressure record. In addition intro- 

 duce a long glass cannula into the opposite carotid artery and 

 prepare the jugular vein for transfusion. 



Take a normal blood-pressure record for comparison. While 

 this is being taken, remove the clamp from the opposite carotid 

 until 50 c.c. of blood have been shed. Note any change in blood 

 pressure during the bleeding. Shut off the artery after the loss of 

 the 50 c.c. of blood. If the pressure has fallen during the hemor- 

 rhage, does it continue low or does it recover after the bleeding 

 has ceased? Explain. 



Bleed again another 50 c.c. of blood. Is there any further fall 

 in pressure ? If so, does it again rise after the cessation of the hem- 

 orrhage ? 



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