( 598 ) 



Summarising we arrive at the following conclusions: 



A. the chronotropy, produced by stimulation of tiie vagus, may 

 be reduced to a negatively catalytic action on a chemical process 

 which lies at the bottom of the pulsation. 



B. the inotropy admits by analogy of a similar interpretation, but 

 il is impossible to prove this, since at present no times of equal 

 change can be determined here. 



As secondary results we mention: 



a. the existence of twofold negatively chronotropic fibres in the 

 right vagus of the tortoise. 



b. a particularly great sensitiveness of the heart of the tortoise for 

 inotropy of the auricle by vagus stimulation, in such a degree that 

 a single condensator discharge may produce the stated moditication 

 and that also with cumulative stimulation it appears sooner and 

 lasts longer than the chronotropy. 



c. the occasional occurrence of spontaneous cardiac turbulence in 

 a warmed tortoise heart, immediately after a principal retardation 

 brought about by vagus stimulation. 



E R R A T ü M. 



In the Proceedings of the meeting of December 29, 1906. 



p. 504, line 13 from the bottom : for 2 read 4 



p. 511, line 5 from the top: for 0.052 read 0.104 



(February 21, 1907). 



