Although knowledge about the nature of the changes which analeptics1produce in cells is almost totally lacking, the drugs now in use as analeptics fall into four convenient categories: Those which have a primary stimulant action on the nervous system and the value of which depends on that action. The representatives of this group are picrotoxin, metrazol® (pentamethylenetetrazol), nikethamide (coramine®), strychnine, caffeine and atropine; the latter three may be regarded as obsolescent or (particularly atropine) obsolete for analeptic purposes. Drugs the analeptic effects of which are due to reflexes from one source or another. The most powerful of such reflexes are those from the carotid and aortic bodies. Alpha lobeline owes its therapeutic action to the stimulation of these structures. Cyanides, sulfides and nicotine are capable of similar actions but are not used because of their extremely toxic properties and connotations. Irritants of the nose, mouth and