208 INTERNAL SECRETION 



solution of i :2O million. The amount of contraction is 

 dependent, within certain limits only, upon the size of the dose. 

 When employing this method as a quantitative test, the degree of 

 contraction must not be taken as the standard ; the latter is 

 obtained by accurate estimation of the degree of concentration 

 which will produce a typical tonic increase. Of the biological 

 tests for adrenalin, registration of the uterine contraction is 

 undoubtedly the most effective. 



The Hair Muscles. As Lewandowsky pointed out, supra- 

 renal extract produces a contraction of the erector muscles of the 

 hair in cats, and an erection of the quills in sea-urchins. Langley 

 next discovered that, in the cat, the erection of the hair of the 

 head takes place in the same w r ay after extirpation of the superior 

 cervical ganglion and degeneration of the post-ganglionary 

 fibres. Taking this finding in conjunction with the fact that all 

 the pilomotors are included in the sympathetic system, he con- 

 cludes that suprarenal extract exercises a direct influence upon 

 the unstriated muscle-fibres of the hair. 



The unstriated muscles of the skin show a remarkable 

 departure from the phenomena usually associated with the action 

 of adrenalin and the results of sympathetic stimulation. The 

 back and tail hairs of cats stand up immediately in response to 

 stimulation of the corresponding sympathetic fibres, but they 

 react only slightly and tardily to the injection of even large doses 

 of adrenalin. In the ape, the hairs are observed to move upon 

 the temples and forehead only. In the dog, the injection of 

 adrenalin is followed by the erection of the hairs of the neck, 

 and in Herpestes mungo by prompt erection of the tail hairs. 



Elliott believes that the difference in the behaviour of the 

 erector muscles of the hair is attributable to differences in the 

 demand made upon them under normal conditions. The English 

 domestic cat rarely puts up its hair, while the hair of the mongoose 

 rises in response to every passing emotion. Thus, in the latter 

 species, adrenalin acts very promptly upon the hair. The 

 feathers of birds have a sympathetic innervation, and adrenalin 

 causes erection in this case also ; it is best seen in the cock, 

 and is less clearly marked in hens and pigeons. Elliott found 

 in the case of his own skin, the hair muscles of which normally 

 possessed a very sensitive reaction, that subcutaneous injection 

 of .03 mg. adrenalin produced a stronger effect upon the hair 

 muscles than upon the vessels. 



The Bronchial Muscles. According to Einthoven, Beer, 

 Brodie, and Dixon, the involuntary muscles of the bronchi receive 

 their innervation from the vagus nerve. Stimulation of this 

 nerve produces a contraction of the bronchi, and consequent 

 contraction of the bronchial tubes. According to Roy and 

 Brown, and also to Sandemann, the vagus contains fibres which 

 cause the bronchial muscles to expand. As far as we know at 



