PLATK LXXXVIII 



FIG. 217. Stage f,>r mi's..|itery ot frog ( 44). 



FIG. 218. Cannulse for aorta and <</< i-ni'n of frog. 

 The right-banil figure represents the arterial CMUraU. 

 They are o size suitable lor large specimens of i{. 

 escitlenta ( 46). 



FIG. 219. Diagram of arrangement for measuring 

 objects seen under the microscope, a. Axis of tulw 

 of microscope. 6. Prism, d. Direction in which the 

 object is seen. c. Surface of drawing-board, which should 

 be at a distance of 10 inches (25 centimeters) from th- 

 eye. The angles of the prism being equal, the angle 

 a 6c = 6o ( 48). 



FIG. 221. Griffin's blower and expanding regulator, as use<l for gas blow-pipe. The blower is used 

 respiration (tee 49)- 



rartiflcia! 



FIG. 220. < 'annul.! f.n- Injecting any liquid 



