PHYSIOLOGICAL DEMONSTRATION 237 



being sunk in the heart. The motions of the heart, which can 

 be kept beating rhythmically by well-known methods, are 

 thus readily projected, as shown by the disc on a point at/. 



The same apparatus projects the contractile movements of 

 pieces of muscle. The plate a is removed, and the arm h 

 arranged above the lever fc d. To a loop on h is fastened one 

 end of the muscle, and to a thread attached to fed the other 

 end ; when the contraction of the muscle will affect the lever 

 as before. 



Czermak's projecting Cardioscope employs the direct optical 



Fio. 124. Action of the Cardioscope 



method of the reflecting mirror. Small slabs of cork are laid 

 on the pulsating body, so as to receive the motion without 

 loss or suppression by weight, and resting upon these are the 

 horizontal arms of very light levers bent at their pivots some- 

 what like an L, which communicate the angular motion to 

 light thin mirrors. Fig. 123 represents such an apparatus 

 with two slabs and mirrors, one slab being placed on the 



