IOWA ACADEMY OF SCIENCE 



127 



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lumen of 1-2 to 1-3 that of the control while they were of the same 

 size at the beginning of the experiment. This experiment was repeated 

 a sufficient number of times to give us conclusive evidence that the 

 muscle tissue of the vein is stimulated by the adrenalin and that it will 

 cause in the excised external juglar vein a marked constriction of the 

 lumen. 



Theoretically this i.s what we should expect as the muscle tissue which 

 is present in the vein i,o well supplied with sympathetic nerve fibres, 

 and according to the work of Thompson, Langley and Bancroft, they 

 have, when stimulated a true constricting influence upon the vein. It 

 has been further shown that the action of epinephrin is similar to the 

 effect of stimulating the sympathetic fibres supplying the muscle tis- 

 sue. Thus in the circulatory system it is a constrictor influence while 

 in the intestines it causes a relaxation of the muscle. If the analogy 

 between sympathetic action and epinephrin is correct the contraction 



