750 PHYSIOLOGY 



effected, not by the endothelial cells of the blood-vessels, but by 

 the gland-cells themselves. The secretion passes from the blood- 

 vessels first into the lymphatic spaces, whence it is taken up by 



FIG. 324. Tracing of volume of sub-maxillary gland, showing effect of stimu- 

 lation of the chorda after administration of 10 mg. atropine. The blood- 

 pressure (lowest line) was unaltered by the stimulation. (BUNCH.) 



the secretory cells. If the first act in secretion consisted in an 

 increased exudation of fluid from the blood into the lymph spaces 

 the first effect of exciting the chorda tympani nerve should be to 

 cause an accumulation of fluid in the lymph spaces, some increase 



FIG. 325. Tracing of volume of sub-maxillary gland showing decrease on 

 excitation of chorda. ( BUNCH.) 



in the lymph flow from the gland, and the swelling of the whole 

 gland. By placing the gland in a plethysmograph we can record 

 the actual changes in its volume which ensue on excitation of the 

 chorda tympani. If all secretion be prevented by the previous 



