970 



SEC. 18. BIOLOGY. 



visible in the second compartment of the box, audible, or sensible at another 

 part of the skin. So we learn the time between two impressions on the same 

 sense, or on two different senses, which enables us to judge about the priority. 

 In order to prevent, under all circumstances, the sparks from passing from 

 one ring to the other, a somewhat greater distance between the rings is 

 desirable. 



PROFESSOR MAREY'S APPARATUS FOR OBSERVING AND REGIS- 

 TERING PHYSIOLOGICAL AND MECHANICAL PHENOMENA. 



3997. 1. Cardiac sounds for indicating the pressure in the 

 cavities of the heart. A. Sound for the right heart. B. Sound 

 for the left heart. C. Sound for showing negative pressures. 

 D. Sphygmoscope, (The corresponding tracings are given in 

 Plate I., 1-4. 



2. Explorator for the heart of the rabbit. (Plates 2 and 2 

 quater.) 



2 A. Explorator for the human heart. (Plate II.) 



Membrane explorator, for the pulsation of the heart, applicable to man or 

 animals. By turning the regulating screw the button of the explorator may 

 be made to project more or less, thus increasing or diminishing the sensitive- 

 ness of the instrument. 



3. Explorator for the pulse (sphygmograph of transmission). 

 (Plate III.) 



4. Explorator for the respiratory movements. (Plate IV.) 

 o. Myographic pincers. 



5 A. Myographic pincers, another pattern. 



6. Explorator for the investigation of to-and-fro movements, 

 such as those of locomotion (of the horse), and of flight (of birds). 

 (Plate VI.) 



