684 



SCIENCE. 



[N. S. Vol. XX. No. 516. 



and in others more serious, of presenting a 

 mirror reversal of the views. The views like- 

 wise appear somewhat small, though it would 

 be easy to introduce lenses to magnify them. 

 But the interest in the device is merely in its 



THE NATURE OF THE ACTION OF DRUGS ON THE 

 HEART (preliminary NOTe).* 



The analysis of the nature of the action of 

 drugs and certain inorganic substances in 

 solution on the isolated heart of vertebrates 



Fig. 2. The apparatus as seen from above, 

 projected by the eyes in stereoscopic vision; 

 and left eyes from cards to mirrors and back.* 



simplicity and in the fact that so direct an 

 application of the Wheatstone plan should 

 have lain so near at hand for so long a time 

 and, to my knowledge, not have been inten- 

 tionally sought for or accidentally hit upon by 

 the many experimenters who have contributed 

 to the literature of the stereoscope. And it 

 is also fair to add that the practical prepara- 

 tion of a pair of mirrors at this angle is not 

 an easy matter, if one is desirous of elimin- 

 ating the seam or line at their point of junc- 

 tion the presence of which to some extent 

 mars the perfection of the stereoscopic effect. 

 It seems, however, worth while thus briefly 

 to record the possibility of a reflecting stereo- 

 scope which is adaptable to the ordinary 

 stereoscopic card. As a laboratory device for 

 illustrating the variety of applications of the 

 stereoscopic principle, it may possess interest 

 if not value. 



Joseph Jasteow. 

 Univeesitt or Wisconsin. 



* In this diagram no account is taken of a 

 minor discrepancy due to the fact that stereo- 

 scopic photographers 1 have agreed upon a separa- 

 tion (and size) of the stereoscopic views (3-3%") 

 greater than the interooular distance (2%-2y2"). 

 As a result practically so much of the views as 

 corresponds to the interocular distance becomes 

 completely stereoscopic, the marginal portions not 

 participating in the stereoscopic effect. Yet for 



Fig. 2. 



The letters as above: V, the combined view as 

 r, r and I, I, the paths of the rays in the right 



is rendered difficult by tte intimate connec- 

 tion of the nervous with the muscular ele- 

 ments in the heart, making it practically im- 

 possible to study the effects of a solution on 

 the nervous elements apart from that on the 

 muscle, and vice versa. In the heart of 

 Limulus the relation of the nervous to the 

 muscular elements is such that this analysis 

 can be made. The heart of Limulus can be 

 prepared in a manner allowing the determin- 

 ation of the nature of the action of a solu- 

 tion: (1) On the ganglion cells, (2) on the 

 motor nerves, (3) on the motor nerve endings 

 and the muscle. 



I have shown elsewhere that in Limulus 

 the origin of the heart-beat is nervous, not 

 muscular, and that the coordination or con- 

 duction in the heart is effected through the 

 nervous, not through the muscular tissue. I 

 have some evidence that a similar mechanism 

 of the heart-beat obtains also in the molluscs 

 and the crustaceans, and I have little doubt 

 that we shall have to revise the generally ac- 

 cepted theory of the function of the ganglion 



ordinary views this discrepancy is not serious; 

 none the less the effect in views mounted within 

 the limits of the interooular distance is distinctly 

 more perfect. 



* The experiments were performed at the Marine 

 Biological Laboratory, Woods Hole, Mass. 



