( 693 j 



XX, — On the Connection between Chemical Constitution and Physiological Action. 

 Part II. — On the Physiological Action of the Ammonium Bases derived from 

 Atropia and Conia. By Dr A. Crum Brown and Dr Thomas R. Fraser. 



(Read 18th January 1869.) 



Atropia. 



Atropia is a nitrile base, obtained from Atropa Belladonna. All we know of 

 its constitution is, that by the action of strong acids and bases it is decomposed, 

 in accordance with the equation — 



C 17 H 23 N0 3 + H 2 = C 9 H 10 O 3 + C 8 H 16 NO* 



Atropia. Water. Tropic Acid. Tropia. 



So that atropia may be considered as tropia, in which one atom of hydrogen has 

 been replaced by tropyl, the radical of tropic acid. 



Atropia has a somewhat complicated physiological action, for it directly 

 influences the functions of the cerebro-spinal and sympathetic nervous systems. 

 The principal effects produced by it on the former system are paralysis of the 

 sensory and motor nerves, and excitation of the spinal cord. By its action on 

 the sympathetic nerves, it influences the contraction of the unstriped muscles ; 

 but as the mechanism of this action is by no means exactly defined, we shall merely 

 allude to it in our comparison of the actions of the methyl and ethyl derivatives, 

 with those of the alkaloid itself. In addition to these general actions, atropia 

 influences, in a special manner, the functions of the vagi nerves and of the 

 iris, suspending the cardiac inhibitory power of the former, and producing 

 contraction of the latter. 



To cause death in the lower animals, it is necessary that atropia be adminis- 

 tered in comparatively large doses, even when it is exhibited by subcutaneous 

 injection. Thus, the minimum fatal dose of sulphate of atropia for a dog, weigh- 

 ing eight or nine pounds, is about fifteen grains ; for a full-grown rabbit, more 

 than fifteen grains ; and for a frog, a dose equivalent to the yoV^th or the ¥ -J-^th 

 of its weight. 



Iodide of methyl- atr opium. — Iodide of methyl acts very readily on atropia ; a 

 good deal of heat is produced; and after the reaction is over, the iodide of 



* Kraut, " Annalen du Ch. u. Ph." band cxxviii. 1863, p, 280; band cxxxiii. 1865, p. 87; 

 band cxlviii. 1868, p. 236. Lossen, ibid, band cxxxi. 1864, p. 43 ; band cxxxviii. 1866, p. 230. 



VOL. XXV. PART II. 8 S 



