Paton and Zaimis (1949) showed that the members of a series of compounds composed of two tri-methyl ammonium groups linked by a polymethylene chain had various actions, such as producing neuro-muscular blocking, inhibition of cholinesterase, a muscarine-like action and a blocking of impulses at the autonomic ganglia. It has been found that hexamethonium is the most active of the above compounds in these respects, and the autonomic ganglionic blocking properties have clinical applications. Hexamethonium is usually used clinically as a dibromide.