316 OF THE CIRCULATION OF THE BLOOD. 



muscular tissue, rendering it incapable of responding to the sti'ongest stim- 

 uli. And others, again, indirectly influence the force and frequency of the 

 heart's action by their action on the respiratory, or upon the vaso-motor 

 systems of nerves. When it is remembered that different animals are not 

 affected in the same manner by particular poisons, and that there is fre- 

 quently a difference between the effects of large and small doses, it may be 

 conceived that the difficulty of explaining the phenomena observed is ex- 

 treme. It may be observed, however, 1 that some poisons, as the Autiaris 

 toxicaria;" Taughinia venenifera; 3 Digitalis; Helleborus niger; Helleborus 

 viridis; the green resin obtained from the Nerium oleander; 4 Squill; Mau- 

 gauja, from the Zambesi River (Dr. Sharpey); and Carroval and Vao, from 

 the river Darien ; 5 most of which have been examined by Drs. Fagge and 

 Stevenson, produce in frogs a peculiar form of irregularity in the action of 

 the heart, attended with protrusion of its walls at different points, and ac- 

 celeration of its beat; then diminished frequency, caused by protraction of 

 the ventricular systole; and finally, stoppage of the contractions by cessa- 

 tion of the dilatation of the ventricles, which remain contracted, white, and 

 perfectly empty. The stoppage usually occurs in from five to twenty min- 

 utes after the administration of the poisonous dose, and the animal retains 

 its control over the voluntary movements for a quarter of an hour or more 

 after the heart has ceased to beat. Calabar bean, ou the other hand, accord- 

 ing to Dr. Fraser, is a poison that produces cardiac paralysis in an exactly 

 reverse manner. It causes no acceleration ; by exciting the vagal centres 

 it diminishes the frequency of the contractions by prolonging the ventric- 

 ular diastole ; and it produces the final stoppage by cessation of the con- 

 traction of the ventricles, which then remain dilated, dark, and full of 

 blood. 6 The Atropiu group of bases, viz., atropin, hyoscyamiu (which is an 



1 See T. R. Fraser, M.D., On the Physiological Action of the Calabar Bean, 

 Physostigma venenosum, from the Transact, of the Roy. Soc. of Edinb. , vol. xxiv, 

 1867, and the paper, On the Application of Physiological Tests for certain Organic 

 Poisons, and especially Digitalin, by Dr. Fagge and Dr. Stevenson, in Guy's Hosp. 

 Reports, 1846, p. 47. 



2 Neufeld, Stud, cles Physiol. Instit. zu Breslau, 1865, Heft 3. 



3 Pelikan and Dybkowski, C. Rend., 1850, p. 1209. 



4 Pelikan, ib., 1866, p. 237. 



5 Hammond, Amer. Journ. of Med. Sci., 1859, July, p. 13. 



6 Arsenious Acid (Cunze, Zeits. f. Rat. Med., Bd. xxviii, p. 33, and Sklarek, 

 Reichert's Archiv, 1866, p. 481), bromide of potassium (Eulenberg and Guttmann, 

 Comptes Rendus, 1867, p. 1281), the salts of barium and of oxalic acid i('\cm, 

 Reichert's Archiv, 1866, p. 196), chloroform (P. Q. Brondgeest, Nedcrland. Archief, 



1865, p. 473, and Dogiel, Reichert's Archiv, 1866, pp. 231 and 415), nicotin, quinine 

 (Eulenberg, Comptes Rendus, 1867, p. 421, Solyet. ibid , 1867, p. 719), strychnia 

 (Heineman, Virchow's Archiv, xxxiii, p. 394), the arrow poison of Borneo (Braid- 

 wood, Edin. Med. Journ , Aug. 1864), aconitina ( Achscharumow, lleichert's Archiv, 



1866, p. 281), caffein and thein (Leven, in Brown-Sequard's Archives de Physiol- 

 ogic;, 1868, p. 481), delphinin (Bohm, Centralblatt, 1871, p. 586), muscarin (Sehmiede- 

 berg, Ludwig's Arbeiten, Bd. v, 1871, p. 41 and Bd. vi, 1872, p. 34), and the gases 

 sulphuretted hydrogen (Kaufmann and Roscnthal, Reichert's Archiv, 1865, Heft 6), 

 hydrocyanic acid (Prcyer, Archiv f. Path. Anat., Bd. xl, p. 125), carbonic oxide 

 (Pokrowsky, ibid., 1866, Heft 1, and Traube, Centralblatt, No. 10, 1866), carbonic 

 acid (Cyon, Comptes Rendus, 1867, p. 1U49), or blood saturated witli them, seem all 

 to exercise a depressing influence upon the motor ganglia of the heart, causing it to 

 stop in diastole, in some instances (aconitina), with, in other (delphinin) without, a 

 preliminary stage of accelerated frequency of beat and augmented blood-pressure. 

 When the, stoppage in diastole is sudden, as occurs when blood charged with carbonic 

 acid is transmitted through the heart, the effect may with probability be referred to 

 direct stimulation of the extremities of the pneumogastrie or inhibitory nerves. Cin- 

 cliunin accelerates the action of the heart (Klson, Amer. Journ. of Med. Science, 

 1866, July, p. 9). Atropin (v. Bezold and Blobaum, Unters. aus der Physiol. Labor. 



