20, 6 Garcia and Guevara: Datura alba 605 
1 per cent pilocarpine on the submaxillary gland. This quantity 
of the preparation of Datura alba did not paralyze the submax- 
illary gland, but abolished completely the response of the chorda 
tympani to electric stimulation. The quantity of pilocarpine 
which completely antagonized 4 centimils of the aqueous prep- 
aration of Datura alba was between 11 and 16 decimils of 1 
per cent pilocarpine. 
The cessation of salivary secretion after the administration 
of Datura alba may be attributed to one of two causes; namely, 
to paralysis of the chorda tympani or to paralysis of the secret- 
ing cells themselves. Since Datura alba stops the secretion of 
saliva caused by pilocarpine which stimulates the end of the 
chorda tympani, and since the gland cells are not paralyzed, 
Datura alba must act by paralyzing the end of the chorda tym- 
pani. Therefore, its manner of action on the salivary glands 
is identical with that of atropine and its allies. 
ACTION ON THE INHIBITORY FUNCTION OF THE VAGUS NERVES 
The action of Datura alba on the inhibitory function of the 
vagus nerves was studied in dogs. The animals were anzsthe- 
tized with morphine and chloretone, and prepared for blood-pres- 
sure tracing and for intravenous injection through the femoral 
vein. Both vagus nerves were cut, and the peripheral ends were 
prepared for electric stimulation. The response to induced cur- 
rent of the vagus nerves under the influence of large and small 
doses of the aqueous preparation was observed. The vagus 
nerves were paralyzed in one minute after an intravenous in- 
jection of 8 centimils, or 1.6 centimils per kilogram of body 
weight, of the aqueous preparation of Datura alba. The paraly- 
sis of the right vagus in one of our animals was complete for 
about twelve minutes. Then it gradually disappeared and com- 
plete recovery occurred one hour and seven minutes after the 
administration of the drug. At that time the left vagus had 
only slightly recovered. 
The inhibitory power of the vagus is weakened by small doses 
of Datura alba. In one of our experiments, the effect occurred 
soon after the injection of 0.0005 mil of the aqueous prepara- 
tion per kilogram of body weight and persisted for about ten 
minutes. The vagus nerve recovered completely in fourteen 
minutes. When the dose was repeated, depression of the vagus 
occurred again, but complete recovery of the nerve was pro- 
longed to twenty-five minutes. With twice this dose, depression 
