MOTOR EXCITANTS. 99 



talis contains five principles — viz. 1. Digitalin, 

 amorphous, soluble in alcohol, insoluble in water, 

 and is the active ingredient of digitalinum, U. S. P. 



2. Digitoxin, insoluble in water, slightly soluble in 

 alcohol, but the most active of all. 3. Digitalein, sol- 

 uble both in water and alcohol. 4th. Digitonin, solu- 

 ble in water, but only slightly soluble in alcohol. It 

 is quite active, but, like saponin, forms a solution 

 which froths readily and antagonizes the three first 

 mentioned. 5. Digitin,. which is apparently inert. 

 The first three are cardiac poisons, the fourth antag- 

 onizes them ; all five are non-nitrogenous, and, except 

 digitin, are glucosides. Digitalis contains no true 

 alkaloid. 



Peepaeations. — Folia Digitalis Pulvis, pow- 

 dered digitalis leaf. Dose: H., gr. xv.-3ss. ; D., 

 gr. i.-iij. 



Extractum Digitalis, solid extract of digitalis. 

 Dose: H., gr. v.-xv. ; D., gr. ^i. 



Extractum Digitalis Fluidum, fluid extract of 

 digitalis. Dose: H., Tlixv.-xl. ; D., th, i.-iij. 



Tinctura Digitalis, tincture of digitalis (fifteen 

 percent). Dose: H., fl. 3ij.-v. ; D., Til iij.-xiij. 



Infusum Digitalis, infusion of digitalis. Dose: 

 H., fl. f ij.-iv. ; fl 3 i.-iv. (digitalis leaf 3, cinnamon 



3, boiling water 185, alcohol 15, water to make 300 

 parts). 



Digitalinum, digitalin. Dose: H., gr. i-i; D., 



Physiological Action. — Digitalis is a cardiac 

 tonic and vascular stimulant, a motor excitant, para- 



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