20, 6 Garcia and Guevara: Datura alba 607 
the aqueous preparation of Datura alba is approximately equiy- 
alent to 0.0025 milligram of either atropine or hyoscine in 
depressing the vagus. Hyoscyamine is slightly weaker than 
Datura alba, hyoscine, or atropine. In other words, 1 mil of 
the aqueous preparation of Datura aiba seeds is equivalent to 
5 milligrams of either atropine or hyoscine. Since the aqueous 
preparation and the fluidextract were found, by biological assay, 
to be equal in strength, and 1 mil of fluidextract represents 
1 gram of the seeds, therefore 5 milligrams of atropine or hyo- 
Scine are equivalent to 1 gram of Datura alba seeds; or, in other 
words, the alkaloidal content of Datura alba seeds is 0.5 per cent. 
This result is almost similar to the alkaloidal content found by 
Bacon(1) and by Brill(3) in air-dried seeds of the Philippine 
Datura alba, using the chemical method. 
Browne, (4) working with flowers of the Chinese Datura alba, 
obtained 0.485 per cent of total alkaloids which he regarded as 
all hyoscine. Hesse(8) found, however, with flowers provided 
by Browne, 0.55 per cent of total alkaloids of which approx- 
imately 92 per cent was hyoscine, 6 per cent hyoscyamine, and 
2 per cent atropine. We have not ascertained whether or not 
the preparation we used contained mostly hyoscine. 
THERAPEUTIC DOSES 
The therapeutic doses of Datura alba seed may be estimated 
from the alkaloidal content obtained, or from the dose required 
to depress or to paralyze the vagus inhibitory nerves. In the 
former case, if the alkaloidal content is 0.5 per cent and the 
predominating alkaloid is either hyoscine or atropine, whose 
pharmacopeeial doses are from 0.3 to 0.6 milligram, the cor- 
responding therapeutic doses of Datura alba seed would be ap- 
proximately from 0.06 to 0.12 gram, and of the fluidextract 
from 1 to 2 drops. As to the latter we found that 0.001 mil 
of the aqueous preparation or 0.001 gram of Datura alba seed, 
per kilogram of body weight, depresses or nearly paralyzes the 
vagus inhibitory nerves. For an adult, weighing 60 kilograms, 
the therapeutic dose would be 0.06 gram. In either case, there- 
fore, the therapeutic doses obtained by calculation are similar. 
SUMMARY AND CONCLUSIONS 
1. The effects of toxic doses of Datura alba in dogs and cats 
correspond to those produced in man. In large doses it produces 
excitement, then incodrdination, and, lastly, depression with 
tendency to sleep. 
