164 GLANDS IN HEALTH AND DISEASE , 



that the adrenal glands are affected through ner- 

 vous channels when a sensory trunk (the main 

 stem of the nerve) is strongly excited, and that 

 they then pour their secretion into the blood 

 stream. 1 



It must be remarked that the inhibitory influ- 

 ence on the beating intestinal strip is shown by 

 adrenaline, which of course suggests that the in- 

 hibition described in this experiment is the result 

 of an increased activity of the adrenals, with a 

 consequent increased production of adrenaline. 

 This adrenaline is discharged into the blood. If 



is added to the solution, or when blood containing a quantity of 

 adrenaline above the trace that is probably found normally, then 

 the tracings on the drum show a sudden jump. For details we 

 must refer the reader to any standard textbook of physiology. 

 Stewart's includes a number of interesting practical exercises. 



1 For the benefit of some readers who may desire more detailed 

 information, the following additional points in Cannon's pro- 

 cedure are appended: The segments of rabbit intestine were sus- 

 pended lengthwise in a glass cylinder through which oxygen waa 

 passed. The segment, when not surrounded by the blood to be 

 tested, was bathed in Ringer's solution (see above). The test 

 blood, the cylinder and the fresh Ringer's solution were all kept 

 at body temperature in a common bath. The blood to be tested 

 was taken before and after the experimental procedures by pass- 

 ing a catheter (a tubular surgical instrument for discharging 

 fluid from a cavity of the body) through an incision in the 

 femoral vein (referring to the thigh) into the iliac (the haunch- 

 bone or the flank) and thence into the inferior vena cava an- 

 terior to the entrance of the lumbo-adrenal veins. A thread tied 

 tightly around the catheter marked the point to which it was 

 inserted and permitted reinsertion to the same point in subse- 

 quent sampling of the blood. The position of the catheter open- 

 ing, which was at one side, was kept constant by attention to the 

 position of the knot in the thread. Thus both the control blood 

 and the blood after stimulation were taken as -exactly as possible 

 from the same region. 



