The more classic of these motor depressants is curare, but conium, because of its more extended use in therapy, will be first considered. Gelsemium, a third member of the group, may be said in a general way to pertain to both the atropine-cocaine and the curare groups, as it shows characteristic reactions of both.

A large number of drugs may be spoken of as motor depressants - thus, the entire alcohol group reduce motor power, and many others, nicotine, aconite, etc., but it is preferred to group here only those in which the principal medical uses are to depress the motor mechanism and lessen reflex excitability.