16 
experience with subcutaneous injections of adrenalin in normal 
rabbits warrants the conclusion that dilation does not occur unless 
the dose is large enough to cause asphyxia. If, however, the superior 
cervical ganglion is excised, even a moderate dose, 0.6 c. c. of a 1 : 1,000 
solution, vdll cause the pupil on the side from wliich the ganglion is 
removed to become dilated od maximum. Radziejewski (63) was one 
of the first to claim that adrenalin instilled into the eye exerts no 
effect upon the pupil, and this idea is supported by Lewandowsky 
(1889), Boruttau, Meltzer, Loevd, Ehrmann, etc. Meltzer (55), 
however, finds that removal of the superior cervical ganglion and 
instillations of adrenalin twenty-four hours later made the pupil dilate 
in proportion to the amount of adrenalin instilled. After four or five 
instillations, two drops every two or three minutes, the dilation can 
be ad maximum, lasting several hours in rabbits and cats (54). 
Meltzer and Auer (56) in a later series of experiments showed that 
adrenalin subcutaneously injected into frogs or instilled into the eye 
dilated the pupil vddely, the vertical axis being affected most. Three 
drops of a 1 : 1,000 solution instilled by pusliing a fine pipette between 
the bulbus and the lid caused very marked dilation in three to seven 
minutes, which lasted as long as if subcutaneous y injected. To 
eliminate the possibility of the drug being absorbed by the skin the 
bulbus was excised and adrenalin dropped upon the corneal surface. 
There was prompt dilation, which lasted many hours. As a result of 
tills work the writers suggested that ‘‘the frog’s eye excised or in situ 
might prove to be a better reagent than the blood pressure to demon- 
strate the efficiency of a suprarenal preparation.” 
Wessely (76) (1905-6) reinvestigated the action of adrenalin upon 
the intraocular pressure and upon the pupil. He found that instilla- 
tions of adrenalin into the eyes of vertebrates causes dilation, provided 
the strength of the solutionis increased to suit the animal experimented 
vdth. For man a 1 per cent solution is accompanied by danger, and a 
0.1 per cent solution is too weak to cause mydriasis. 
Schultz (66) also showed that adrenalin instilled into the* eyes 
of mammals always causes dilation of the pupil. The degree of 
mydriasis resulting from a given amount of adrenalin depends, 
however, upon the intensity of light stimuli and upon the kind of 
animal used. There is, so to speak, a kind of antagonism between 
the processes set up by the light stimuli and those initiated by 
adrenalin. So that animals with a sensitive and more highly devel- 
oped light-accommodating mechanism require a longer period of 
instillation and a greater amount of adrenalin to cause mydriasis 
than those vdth eyes less sensitive to light. 
Ehrmann (29) (1905) used the method suggested by Meltzer (56), 
and thinks to have ruled out the influence of the sympathetic im- 
