THE SUPRARENAL SYSTEM 211 



out whether mydriasis takes place under certain special conditions, 

 in which a suppression of the sympathetic inhibition is assumed. 

 He found that, after the instillation of adrenalin into the con- 

 junctiva, enlargement of the pupil was invariable in dogs and 

 cats from which the pancreas had been removed; that it was 

 occasional in artificial pancreatic insufficiency; and that it was 

 present in many clinical instances of diabetes and Graves's 

 disease. Lowi assumes from this that the inhibition of certain 

 organs with a sympathetic innervation is a normal function of 

 the pancreas. He regards the mydriasis produced by adrenalin 

 in Graves's disease as the expression of an increased irritability 

 of the sympathetic, brought about by hyperthyroidism. This 

 increased irritability is as readily attributable to a suppression 

 of the inhibitory nervous function, as to an increase in th^ 

 stimulatory nervous function. Eppinger, Falta and Rudinger 

 succeeded later in producing adrenalin mydriasis in normal and 

 thyroidectomized dogs by continuous treatment with thyroid 

 extract. 



The Glands. Langley found that, when suprarenal extract 

 is given in moderately large doses, it provokes a profuse secre- 

 tion on the part of all the salivary glands, as well as of the 

 mucous glands situated in the mouth, oesophagus, and trachea. 

 This increased secretion becomes apparent a little later than the 

 rise in blood-pressure, it quickly reaches the maximum, and then 

 gradually subsides. Hence the irritability of the cervical sym- 

 pathetic and of the chorda tympani is not by any means reduced, 

 that of the latter being, in fact, rather augmented. That the 

 secretory stimulus does not proceed from the central nervous 

 system, is shown by the fact that it continues unchanged after 

 resection of the superior cervical ganglion and of the chorda 

 tympani. It is the outcome of peripheral stimulation, and it 

 remains constant, though somewhat diminished in intensity, after 

 comparatively large doses of nicotine. Moreover, atropine, in 

 a quantity sufficient to paralyse the fibres of the chorda, does 

 not inhibit the increased secretion, though this disappears in 

 response to atropine in large doses. It is evident, from these 

 results, that suprarenal extract stimulates those elements whether 

 nerve terminals or glandular cells which are inhibited by the 

 action of atropine. Adrenalin excites the secretion of saliva even 

 after extirpation of the ganglion and degeneration of the post- 

 ganglionary fibres, and this makes it certain that the effect cannot 

 be due to stimulation of the sympathetic nerve terminals. 



Under the influence of adrenalin, the vessels of the sub- 

 maxillary gland contract and the gland blanches ; after an interval 

 of thirty seconds it becomes increasingly red until its colour is 

 deeper than before the injection. The blanching is less than 

 after stimulation of the sympathetic, the flushing less intense 

 than after stimulation of the chorda. Here also, vaso-constriction 



