138 Mr. J. Priestley on Batrachian Lymph-Hearts. [Feb. 28, 



4. The normal rhythm of the heart is dependent on the soundness 

 of certain regions of the spinal cord, viz., for the anterior pair, of the 

 region opposite the 3rd vertebral body (Volkmann*), for the posterior 

 pair, of the region opposite the 6th. This statement is a correction 

 of the view commonly held in respect of the spinal region concerned 

 in the rhythm of the posterior hearts ; for all previous observers seem 

 to have followed Volkmann in saying that the region of the 8th verte- 

 bral body is that implicated. 



If these regions are injured, or if the nerves proceeding from them 

 to the hearts are intercepted, either the hearts are brought to rest per- 

 manently, or their natural pulsation is disorganised and reduced for a 

 long time to more or less irregular fluttering. These spinal centres 

 seem capable of inhibition by strong sensory (afferent) stimuli, even in 

 the absence of the encephalon. 



5. The natural pulsation of the lymph-hearts is constantly controlled 

 from an encephalic inhibitory centre in the optic lobes, separation from 

 which is, therefore, at once followed by increased rate of beat 

 (Suslowa.)f This inhibitory centre is said by Goltz J to be roused 

 into stronger action by powerful mechanical stimuli proceeding along 

 the vagi from the heart, or proceeding from the abdominal viscera in 

 the Klopfversuch. 



6. The disorderly contractions that follow division of the lymph- 

 cardiac spinal nerves may give place to a regular pulsation 

 (Eckhard,§ Schiff,|| Heidenhain ^[). The restoration does not usually 

 take place until after many days, but when established, the rhythmical 

 beating is independent of the spinal cord, not ceasing, like the pulse 

 of normal lymph-hearts, when the central nervous system is destroyed 

 (Goltz,** Waldeyerft)- The cause of these movements is not yet 

 fully understood ; but the movements themselves are abolished by 

 local or general application of curare in solution. 



Action of Electrical Currents on the Lymph-Hearts op Frogs. 



A complete description of the action of electrical currents on the 

 lymph-cardiac mechanism includes the action of induced currents and 

 of constant currents. The latter were generated by Grove's or Daniell's 

 elements, the former by a Du Bois' induction coil. The portions of the 

 lymph-cardiac apparatus tested were brought into the circuit by appli- 



* Volkmann, loc. cit. 



f Suslowa, Centralblatt f. med. Wis. 1867, p. 832. Henle u. Pfeufer's Zeitsch., 

 1868. 



X Groltz, Centralblatt f. med. Wis. 1863, p. 17 ; p. 497. Ibidem, 1864, p. 691. 

 § Eckhard, loc. cit. || Schiff, loc. cit. 



% Heidenhain, Disqnisitiones de nervis cordis, etc. Berlin. 1854. (Dissertation.) 

 ** Goltz, loc. cit. +f Waldeyer, loc. cit. 



