OOTOBEK 6, 1916] 



SCIENCE 



485 



to adrenaline, we can infer that it contains 

 the substance characteristic of the termina- 

 tions of sympathetic fibers, with almost as 

 great certainty as we infer the presence of 

 a phenol group from the reaction with iron. 

 And this sympathetic substance can be fur- 

 ther analyzed into two parts by means of 

 ergotoxine, which reacts with the substance 

 of the motor sympathetic ends, while leav- 

 ing that of the inhibitory terminations un- 

 affected. Similarly the endings of the para- 

 sympathetic nerves are picked out with 

 some exceptions by the groups represented 

 by atropine and pilocarpine, and here 

 again there must be some definite substance 

 which can be detected by these reagents. 



Further, some light has been thrown on, 

 at any rate, one aspect of these nerve-end 

 substances by the observation that they all 

 react to only one optical isomer in each case. 

 Thus the dextro-rotatory forms are ineffec- 

 tive in both atropine and adrenaline, and 

 this suggests strongly that the reacting body 

 in the nerve-ends affected by these is itself 

 optically active, though whether it bears 

 the same sign as the alkaloid is unknown. 

 This very definite differentiation between 

 two optical isomers is not characteristic of 

 all forms of living matter. For example, 

 the heart muscle seems to react equally to 

 both kevo- and dextrocamphor. The cen- 

 tral nervous system contains substances 

 which react somewhat differently to the 

 isomers of camphor and also of atropine, 

 but the contrast is not drawn so sharply 

 as that in the peripheral nerve-ends. 



Another test alkaloid is curarine, the 

 active principle of curare, which in certain 

 concentrations selects the terminations of 

 the motor nerves in striated muscle as defi- 

 nitely as any chemical test applied to deter- 

 mine the presence or absence of a metal. 



The tyro in the chemical laboratory is 

 not often fortunate enough to be able to 

 determine his analysis with a single test. 



He finds, for example, that the addition of 

 ammonium sulphide precipitates a consid- 

 erable group of metals, which have then to 

 be distinguished by a series of secondary 

 reactions. The pharmacologist, as an ex- 

 plorer in the analysis of living matter, also 

 finds that a single poison may affect a num- 

 ber of structures which appear to have no 

 anatomical or physiological character in 

 common. But as the chemist recognizes 

 that the group of metals which react in the 

 same way to his reagent have other points 

 of resemblance, so perhaps we are justified 

 in considering that the effects of our poison 

 on apparently different organs indicate the 

 presence of some substance or of related 

 substances in them.. A great number of in- 

 stances of this kind could be given, and in 

 many of these the similarity in reaction 

 extends over a number of poisons, which 

 strengthens the view that the different 

 organs involved have some common reacting 

 substance. 



One of the most interesting of these is 

 the common reaction of the ends of the 

 motor nerves in striated muscle and of the 

 peripheral ganglia of the autonomic system. 

 It has long been known that curare and 

 its allies act in small quantities on the ter- 

 minations of the motor nerves in ordinary 

 muscle, while larger amounts paralyze con- 

 duction through the autonomic ganglia. 

 More recently it has been developed by the 

 researches of Langley that nicotine and its 

 allies, acting in small quantities on the 

 ganglia, extend their activities to the motor 

 ends in large doses. Some drugs occupy 

 intermediate positions between nicotine and 

 curare, so that it becomes difficult to assign 

 them to either group. These observations 

 appear to leave no question that there is 

 some substance or aggregate common to the 

 nerve-ends in striated muscle and to the 

 autonomic ganglia. As to the exact an- 

 atomical position of this substance, there 



