THE NERVE gases are a group of highly toxic organic esters of phosphoric acid derivatives which have physiologic effects attributable to the inhibition of cholinesterase enzymes. The effects resemble those produced by physostigmine and neostigmine (Prostigmin) but are more intense and more prolonged. The nerve gases are among the most toxic of the chemical warfare agents, and they are the most adaptable to long-range attack, as upon civilian populations.1 A number of related but somewhat less toxic organic phosphate anticholinesterase compounds have proved to be useful in medicine and in agriculture. Diisoprophyl fluorophosphate (DFP) has been studied in detail* and has been employed as a therapeutic agent in the management of abdominal distention,† urinary retention, and glaucoma.6 Tetraethylpyrophosphate (TEPP) 7 and octamethyl pyrophosphoramide (OMPA) 8 proved to be of some value in the management of myasthenia gravis, but they have been replaced by less potent anticholinesterase compounds. Parathion, bis-(monoisopropylamino)-fluorophosphine