140 Canadian Record of Science. 



causes increase in the work done by the heart, hence these 

 nerves should be called augmentors rather than accelerators. 

 Application of the Rapidly Interrupted Current to the Heart 

 itself. In addition to the white dots seen at the points of 

 application of the electrodes and the dilation and blue appear- 

 ance following the use of a weak or moderate current 

 another effect noticed in the alligator, on the use of a very 

 strong; current deserves mention. Prom the part where the 

 electrodes touched the auricle, a considerable area took on a 

 pale, even whitish aspect and seemed to diminish in size ; by 

 gradually moving the electrodes along, more and more of 

 the auricle passed into the same condition. The part involved 

 was thrown out of action, as in the case of the dilated posi- 

 tion. This condition seemed to be one of pronounced con- 

 traction, probably tetanic, and confirms the view that the 

 white dots seen in all cases just where the electrodes touch 

 are caused by the contraction of the muscle fibres. 



THE CARDIAC RHYTHM OP FISHES AND THE ACTION ON THE 

 SAME OP CERTAIN DRUGS AND POISONS. 



The object of the investigation was (1) to ascertain 

 whether there were considerable physiological differences 

 in the hearts of different fishes, and (2) to ascertain the laws 

 regulating the rhythm of some one fish heart specially suit- 

 able for investigation, and (3) to determine the action of 

 certain drugs and poisons on the fish's heart ; these being, 

 many of them, such as have been studied in their influence 

 on the heart of the frog. 



In general it may be said that the hearts of fishes are so 

 sensitive to changes in normal conditions, and that most 

 fishes are so easily killed, that it is not possible to pursue 

 prolonged investigations on their hearts in situ. This re- 

 mark applies especially to the Selachians, whose hearts, from 

 many points of view, are exceedingly interesting. 



Batrachus Tau (toadfish), is a fish of great vitality, resist- 

 ing unfavorable conditions admirably, and its heart has a 

 corresponding vital resistance, and being excellently suited 

 for experimentation, this fish was the subject of a majority 



