NACHMANSOHN: CHEMICAL MECHANISM IN NERVES 413 



of esterase, easily detectable quantities of eserine. The axoplasm of 

 nerves kept in prostigmine had no inhibitory effect on cholinesterase, 

 even when undiluted. 



Prostigmine, like ACh, has 3 methyl groups attached to the nitrogen. 

 Drs. Bronk and Acheson have offered evidence that tetraethylammo- 

 nium chloride acts on medullated nerve and, therefore, presumably en- 

 ters it. This compound is also a quaternary ammonium salt and com- 



MiNo 



MS. 



Figure 7. Effect of prostigmine on fin nerve. 

 O.OIM. Traced from enlarged photographs. 



Records before and after 83', 205', and 370' in 



pletely dissociated. Although it is true that ionized compounds are 

 not readily soluble in lipoids, the properties which decide lipoid solu- 

 bility are far from well established. Frequently, when, in a com- 

 pound, the ratio of C over N is increased, it becomes more lipoid 

 soluble. In tetraethylammonium chloride, there is four times as 

 much carbon as in tetramethylammonium chloride. The change from 



