748 DR FRASER ON THE PHYSIOLOGICAL ACTION 



It is almost needless to remark that the change in the systolic colour of the heart, from pale 

 to dark, did not occur. The heart's surface was prevented from drying by an occasional drop of 

 water ; and this was also done during the experiments in which physostigma was administered. 



We have now sufficiently described, as proposed (p. 743), " the various changes 

 that are undergone by the heart before its contractions finally cease;" and from 

 the data given, these may be summarised in their order of occurrence as follows: — 



1st, Diminution never preceded by increase, of the frequency of the contrac- 

 tions, with prolongation of the period of rest; 2d, Feebleness of the contractions, 

 with no change of colour on the occurrence of systole ; 3d, Irregularity of rhythm, 

 the auricles contracting more frequently than the ventricles, and, for intervals, 

 contracting alone ; 4th, Stoppage of all the heart's chambers — If the poison be 

 absorbed quickly and in large quantity, the fifth and sixth effects may not occur ; 

 5th, Renewal of contractions, either by all the chambers at once, or by one or 

 more in the first place ; 6th, Gradual recovery to a low rate of action, and con- 

 tinuance at this for from a few minutes to several days ; 7th, Stoppage in diastole 

 of spontaneous contractions ; and 8th, Loss of the idio-muscular irritability of 

 the heart, rigor and change of reaction from alkaline to acid. 



This method of affecting the heart distinguishes physostigma from the great 

 majority of cardiac poisons, which may be well represented by Antiaris toxicaria* 

 Tanghinia venenifera,\ Digitalis,X Helleborus niger, H. viridis% and the green 

 resin obtained from Nerium Oleander.^ These produce first irregularity and 

 acceleration of the heart's action, then a diminished frequency, caused by pro- 

 traction of the ventricular systole, and, finally, stoppage of the contractions by 

 " cessation of the dilatation of the ventricles, which then remain contracted, white 

 and perfectly empty." ^[ In producing cardiac paralysis, physostigma acts in 

 a manner exactly the reverse. It causes no acceleration, it diminishes the 

 frequency of the contractions by prolonging the ventricular diastole, and it 

 produces the final stoppage by cessation of the contraction of the ventricles, which 

 then remain dilated, dark and full of blood. Very small doses of digitaline and the 

 alcoholico-aqueous extract of Nerium Oleander are said to act on the heart in a 

 manner which seems to resemble closely that of Calabar bean,** but no other 

 cardiac poisons appear to share in its peculiarities. 



It now remains that we examine the mechanism by which these changes are 

 produced, and endeavour to determine what tissues or structures are influenced 

 by physostigma to effect them. For this purpose, it will be necessary to investi- 



* Kolliker, Vulpian, Claude Bernard and others, in various papers. 



+ M. Eug. Pelikan et Dr Dybkowski ; Recherches physiologo-toxicologiques sur Paction de 

 quelques poisons ducoeur; and Comptes Rendus, 1865, p. 1209. 



X Ibid. § Ibid. || Ibid. 



*[[ On the Application of Physiological Tests for Certain Organic Poisons, and especially Digi- 

 taline, by C. Hilton Fagge, M.D., and Thomas Stevenson, M.D. Guy's Hospital Reports, 3d 

 series, 1866, vol. xii. p. 47. 



** Nouvelles Recherches sur le poison du Nerium Oleander. Note de M. Eug. Pelikan. 

 Comptes Rendus, 1866, p. 237- 



