20, 6 Garcia and Guevara: Datura alba 603 
the aqueous preparation into the anterior chamber of the eye 
caused almost immediate dilatation of the pupil. Full dilatation 
was reached one minute after injection. Stimulation of the 
central end of the vago-sympathetic caused further dilatation, 
while even maximal stimulation of the isolated short ciliary 
nerves was ineffective. Stimulation of the iris through the 
edges of the cornea was also ineffective. However, we failed 
to elicit any effect in either the normal or the atropinized eye 
with this method of stimulation. 
TABLE 3.—Effect of Datura alba on the pupil of a cat. 
[Date of experiment, November 17, 1920.] 
Diameter of pupil. 
Time. Procedure. Right. Left. 
Ss 2d Vertical. ge ga Vertical. 
p.m, mm, mm, mm, mm, 
1 Dh | cdot caolbirigasiniatincacanenmseleleuiaiiangiia Malden r oie eo 1. 3 5 3 5 
Da OO es ee ey 3 5 3 5 
Fee oa os on. pcp on a en ees 8 5 3 rape 
1.37 | 1 drop aqueous preparation applied in right eye___|_._..._.-.|_.______ _|_----__--.|.2----___- 
Ni a a a a ee a aes 3 5 3 5 
BT Toe ae re ee ek eee 3 5 8 5 
ASG Hoo eee aceon cep wie ee ie ee ee 6 8 3 5 
ge) Pee See Mg nape ar een ae eae Gee ccna ne ea ere 9 10 3 5 
a 8 Bea ae Speer ie eer eee mina rec a) 10 10 3 5 
DANE Lope ots pues cap naWan te euece eee ee tae a 10 10 3 5 
OOD cee ccac ios ee ec 10 10 3 5 
The immediate response of the pupil to local application of 
the drug indicates that its site of action is most probably pe- 
ripheral. The action may be either on the dilator or on the con- 
strictor mechanism. The dilator mechanism was probably not 
affected for it still responded to electric stimulation even after 
the administration of large doses. On the other hand, the 
constrictor mechanism was paralyzed, for it no longer re- 
sponded to electric stimulation after application of the drug. 
The iris muscles consist of dilator and sphincter, and, since 
both are smooth muscles, it may be expected that if one is 
paralyzed by direct action of the drug the other will be similarly 
affected. Paralysis of the dilator muscle was not present for 
it still responded to vago-sympathetic stimulation; hence it may 
be deduced that the sphincter was not paralyzed. The action 
may be localized on the oculomotor nerve fibers, on the nerve 
