DIGITALIS. 309 



given in very minute doses ; but afterwards depresses in an 

 extreme degree, causing intense and universal debility, which, 

 with the local irritation of the alimentary canal, constitute a 

 condition of collapse. On analysis, it is found that tobacco 

 causes pleasing cerebral excitement ; decided stimulation of the 

 motor centres in the cord, with a feeling, and true increase, of 

 muscular strength (ending in convulsions and paralysis, in 

 poisonous doses) ; excitation, followed by paralysis, of the 

 peripheral nerves, both sensory and motor ; but no direct effect 

 on the muscles. Eespiration is first excited, then disturbed, 

 and finally arrested, death by tobacco being due to arrest of 

 the centre. The action of tobacco on the heart is, contrary 

 to general belief, not directly the cause of death : it is first 

 slowed, then accelerated, and finally weakened with slowing, 

 but it beats after respiratory death. The blood pressure falls, 

 rises, and falls again, with the cardiac action, and from direct 

 central and peripheral effect on the vasor apparatus. The tem- 

 perature falls. 



Tobacco was formerly employed in enema to produce 

 general muscular debility and relaxation, for the reduction of 

 hernia ; but chloroform has entirely displaced it. Its depres- 

 sant effects suggest its use as an antispasmodic in whooping- 

 cough, asthma, hiccup, tetanus and strychnia poisoning, 

 rigidity of the cervix uteri, etc., but such a powerful drug is 

 very seldom employed. 



4. REMOTE LOCAL ACTION AND USES. 



Nicptin is excreted unchanged in the urine, saliva, and 

 faeces. As a diuretic, it was formerly given in dropsy, but 

 this use of the drug has been abandoned. 



SCROPHULABIACE^. 



Digitalis Folia DIGITALIS LEAVES. The dried 

 leaves of Digitalis purpurea. Purple Foxglove. Col- 

 lected from wild indigenous plants, when about two- 

 thirds of the flowers are expanded. 



Characters. Ovate lanceolate, shortly petiolate, rugose, 

 downy, paler on the under-surface, crenate. 



Substance resembling Digitalis Leaves : Matico, which is 

 more deeply reticulated. 



Composition. The active principle of digitalis, known as 

 digitalinum, or dig it aim, occurs in two forms : (a) Homolle and 

 Qnevenne's digitalin, a yellowish-white amorphous, or scaly 

 very intensely bitter substance ; and (b) Nativelle's digitalin, in 



