EFFE C TS OF EXTRA CTS. 
947 
is also due to contraction of the arterioles, is sufficiently shown by the 
fact that if salt solution containing pituitary extract be passed through 
the blood vessels of a frog, the entire nervous system of which has been 
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destroyed, the vessels markedly contract. This experiment conclusively 
shows that the effect upon the arteries is a direct one, and in all pro- 
bability the action upon the heart is also direct. 
