SOCIETY MEETINGS. 
229 
the effect on voluntary muscles may be said to be negative, but 
upon involuntary muscles, its action is marked ; and upon this 
action the real value of belladonna as a curative agent largely 
depends. It paralyzes the vaso-motor constrictor nerves, espe¬ 
cially of the capillary system, and so increases their lumen as 
to almost produce a pathological condition. The surface of 
the body becomes reddened and engorged with blood, and the 
mucous membranes are affected likewise. The organism is 
brought into a state that eminently resembles the first stage of 
a fever or an inflammatory disease, i. <?., augmented heart’s 
action, with heat, redness, engorgement and dryness of the sur¬ 
face of the body. The capillaries of the lungs being similarly af¬ 
fected the respiratory area is increased. More blood is oxidized 
and more C 0 3 is eliminated. With the heart stimulated into 
increased activity, the capillaries of the great respiratory area 
active and engorged, belladonna acts as a powerful stimulant 
to the respiratory function, a feature possessed by no other drug. 
The periphery of the third nerve is paralyzed and thus the elas¬ 
tic fibres of the iris contract and dilate the pupil. It was once 
said that atropine dilated the pupil by stimulating the sympa¬ 
thetic filaments of the iris, but as this theory has never been 
proven, and since it is difficult to conceive how a drug could 
depress one nerve and at the same time and under the same 
condition stimulate another, it is a statement that deserves no 
serious consideration. When the third nerve is cut the pupil 
dilates precisely as it does when paralyzed with atropine ; 
therefore the mydriatic action of belladonna is easily compre¬ 
hended. 
4. By paralyzing sensory nerves belladonna becomes an 
analgesic, but in this connection it is inferior to opium. When 
applied locally in a more or less concentrated form it does re¬ 
lieve pain, but internally it does not rank high as a pain-killer. 
It does, however, have a soothing effect upon the urinary tract, 
and probably upon the generative organs. 
Brain and spinal cord :—The only medicinal action that 
belladonna has upon the brain and spinal cord is its infirence 
on the respiratory and vaso-motof centres. 
Summary . 
1. Belladonna is a cardiac stimulant, increasing particularly 
the number of heart beats. 
2. It arrests secretions of the skin (antihidroic); the mu¬ 
cous membrane, especially the bronchial ; the salivary glands 
(antisialagogue); and of the mammae (antigalactagogue). 
