LABORATORY MANUAL OF PHYSIOLOGY. 



effect on the flow of secretion ? Does the chorda run directly to the 

 gland cells without interruption? If not, where is the point of 

 transfer ? 



5. Wash the gland thoroughly with warm physiological saline. 

 After a time the nicotine effect will wear off. Isolate and intro- 

 duce a cannula into the femoral vein, centrally. Inject into the 

 vein J grain atropine sulphate. Note the effect on the flow of sa- 

 liva. Stimulate the chorda. Is there an increased flow of the 

 secretion? Empty the duct of secretion. With a hypodermic 

 syringe inject into the duct a few drops of a 2-per-cent solution of 

 pilocarpine nitrate. Stimulate the chorda again. Is any effect now 

 obtainable on the salivary flow ? After several minutes stimulate 

 again. The atropine effect has once more asserted itself. 



Does stimulation of the nerve still cause a dilatation of the gland 

 vessels? Is the effect of the nerve stimulation in causing an in- 

 crease in flow of secretion purely a vaso-dilator effect or is it due to 

 a stimulation of the gland cells themselves ? Explain. 



II. To SHOW CHANGES IN THE GLAND CELLS FOLLOWING 

 CHORDA STIMULATION. 



Make another preparation of submaxillary gland, duct, and 

 nerve. Stimulate the nerve with a weak tetanizing current until 

 the flow of the secretion ceases. Allow an interval of five minutes' 

 rest and repeat the stimulation. Continue to complete exhaustion 

 of the gland. Remove both submaxillary glands. Cut out small 

 portions of each and make frozen sections of the fresh glands. 

 Mount in normal salt solution or in glycerin. Examine sections 

 from the two glands under the microscope. Compare the appear- 

 ance of the cells of the stimulated gland with that of the resting 

 gland. 



Harden the remainder of the two glands in absolute alcohol; 

 embed in paraffin; cut sections; and stain with carmine. Com- 

 pare the stained sections of the two glands with each other and 

 with the frozen sections of the fresh glands. 



