48 
Xos. 242 to 250, inclusive, and 267 and 268, 250 mg. of crystals dissolved in 5 c. c. 
Ringer solution about 1p.m. January 16. 
Xos. 251 to 266 and 269 to 286, inclusive, 250 mg. of cr^’stals dissolved in 5 c. c. 
Ringer solution 3 p. m. January 16 for each set of nine. 
Xos. 287 to 304, inclusive, 250 mg. of crystals dissolved in 5 c. c. Ringer solution 2.30 
p. m. January 20, 1909. 
measuee:mext of mydriasis ix the frog's excised bulbus.^^ 
As is well known the dilator mechanism of the frog's eve is c^uite 
sensitive to adrenalin and not a little emphasis has been laid upon 
the delicacy with which it reacts to minute traces of this and certain 
other derivatives of the catechol group. Because of this mydriatic 
action, the apparent simplicity of the technique involved, and the 
availability of experimental animals, the enucleated eye of the frog 
seems to furnish a suitable method for standardizing adrenalin 
solutions. 
Meltzer was the first to call attention to this method and nearly a 
year later Ehrmann, acting upon Meltzer’s suggestion, published 
some very interesting experiments with the excised frog’s eye. In 
Ehrmann's suggestive paper it is not only sho4vn that adrenalin solu- 
tions of different concentration call forth varying degrees of mydriasis, 
but it leads one to suppose that the enucleated frog's eye is sensitive 
to such minute quantities of adrenalin as may occur in the blood drawn 
from the vena cava. Taking advantage of the sensitiveness of the 
frog's eye he also uses this method as a means for demonstrating the 
activity of adrenalin still in the blood of injected animals bled imme- 
diately after the fall of blood pressure that invariably follows the initial 
effect of this drug. ^ Just how reliable these conclusions are remains 
to be decided by future experiments. Cameron, in his paper on methods 
of standardizing suprarenal preparations, states that the method is not 
only tedious but very unreliable, since frogs vary in their response to 
adrenalin. 
Various factors do inffuence the reaction of the iris to adrenalin. 
Perhaps the most important ones are: (1) Conditions that interfere 
with the frog's normal metabolism and nutrition, (2) the varying 
intensity of light to which the eye is exposed, (3) the temperature 
of the medium surrounding the enucleated bulbus, (4) injuries to 
the coats of the bulbus that may result in lowering the intra-ocular 
tension and alter the rate of diffusion, and, finally, (5) mechanical 
a The section on the pupil was completed Xovember 15, 1908, but publication was 
delayed so that the comparative study herein contained might be made. 
& Dryer as early as 1897-1899 showed that adrenalin is secreted into the circulation 
after stimulation of the splanchnic nerve. This excellent piece of work has not 
received the attention of German writers that it should, especially since Dryer is one 
of the first to prove conclusively that stimulation of the splanchnic causes an in- 
creased secretion by the adrenal glands. 
