248 THE ADRENAL SYSTEM AND VASOMOTOR FUNCTIONS. 



A query that normally suggests itself is the following: 

 What is the experimental value of the current for the deter- 

 mination of the specific function of any nerve when its relative 

 irritability is a sufficiently prominent factor to cause it to in- 

 dicate, under the influence of this current, one function at 

 one time and the opposite function the next? Evidently the 

 variation in irritability must mean either as is the case with 

 the nerves of the parotid gland that the antagonistic nerves 

 are directly connected or juxtaposed or that one is sufficiently 

 metamorphosed organically as to modify its conductivity. 

 Framed in this manner, the query meets with a ready response: 

 Inasmuch as vasoconstrictor and vasodilator nerves accompany 

 the sciatic nerve, they become common conductors when the 

 circuit is closed, and any indication furnished, therefore, is of 

 no scientific value. 



There is another possible explanation, however, viz.: 

 Either one of the dilator or constrictor nerves may be absent 

 in the structures supplied by the sciatic and the brachial 

 plexus. In other words, skeletal muscles may only be supplied 

 with one of these nerves. Yet there is no experimental differ- 

 ence between these and other structures of distribution; thus, 

 section causes vasodilation, while stimulation gives rise to con- 

 striction of the vessels, and, if either of the vasomotor nerves 

 is not supplied to these structures, their motor nerves must 

 fulfill the role of the absent system. We could readily enough 

 state, after eliminating the only evidence in favor of the ex- 

 istence of vasoconstrictors, that there are none in striated 

 muscles, all the positive evidence pointing only to the existence 

 of vasodilators. But we must not lose sight of the fact that 

 we have interpreted the experimental evidence at our disposal 

 in a different manner, and that our own views must also be 

 shown to be in accord with this evidence, if they are to merit 

 confidence. 



From our standpoint, then, granting the existence of both 

 constrictor and dilator nerves, in direct relation with the 

 sciatic, what would be the result of electrical stimulation? 

 None, whatever, diameter, structure, and peripheral elements 

 of the nerves being equal. Function depending on increased 

 blood-supply and perfect balance between vasodilation and con- 



