RECENT PHYSIOLOGY. 83 



muscle he has obtained a great series of marveloiisly beautiful records. 

 Gotch and his pupils, using a similar arrangement, have been able to 

 record the electrical changes in active nerves, even when stimulated by 

 rapidly recurring shocks from an induction coil. It may surprise those 

 who have not followed the progress of technique in the biological sci- 

 ences to learn the extent to which photography is now applied in physi- 

 ological research. Pictm-es of even such feeble vil)rations as those 

 which give rise to the sounds of the heart may be obtained by con- 

 necting a microphone placed near the chest and the primary coil of an 

 induction machine in the same circuit, and photographing the move- 

 ments of a capillary electrometer connected with the secondary. 

 Exquisite photographs of the electrical variations occun-ing in the 

 human heart at each beat, first demonstrated by Waller, have been 

 recently published by Eiuthoven and Lint. 



Loeb, working from another direction, has studied the effect 

 of the ions contained in solutions of certain simple salts 

 on rhythmical contraction in general, and particularly on the 

 rhythmical contraction of the heart. He starts with the observation 

 that a striped muscle in a solution of sodium chloride of a certain 

 strength carries out rhythmical contractions which may last 24 to 48 

 hours. Salts of lime and of potassium hinder the contractions. 

 N'evertheless the muscle remains longer alive when a small amount of 

 calcium or potassium chloride is added to the sodium chloride solution. 

 He explains the seeming paradox by the hypothesis that the sodium 

 ions are the real stimulus for the rhythmical contractions, but yet 

 exert on the muscle a poisonous influence, which, is counteracted by 

 the calcium and potassium ions. He finds support for the idea that 

 the sodium ions are actually poisonous to the living substance in the 

 fact that Fundulus heteroclitus — a small marine fish with so marvel- 

 ous a range of adaptation to its environment that it will live, on the 

 one hand, in sea-water to which sodium chloride has been added to the 

 amount of five per cent., and, on the other hand, in fresh and even 

 in distilled water — -wall not live in pure sodium chloride solutions of 

 about the same strength as sea-water, but will survive in sodium chlo- 

 ride solutions even twice as strong if a little chloride of calcium or of 

 potassium be added. According to Lingle, one of the pupils of Loeb, 

 sodium ions, while acting as the normal stimulus to the discharge ©f 

 rhythmical contractions by the heart muscle of the turtle, exert upon 

 it, in the absence of calcium and potassium ions, the same deleterious 

 influence as upon striped muscle, a fact also demonstrated by 

 Ringer and others for the heart of the frog. These are the experi- 

 ments which that eminent contributor to the gayety of nations, the 

 scientific newspaper reporter, has recently travestied under the caption, 

 'Discovery of the Elixir of Life in Chicago.' They have yielded fresh 



