152 APPENDIX TO CHAPTER XIII. 



f. Carefully raise the wedge-shaped flap of the left ventricle, and 

 cut on towards the base of the heart, until the valve (mitral} between 

 auricle and ventricle is brought into view; one of its two flaps will be 

 seen to lie between the auriculo-ventricular opening and the origin of 

 the aorta. 



Examine in these flaps their texture, the chordae tendineas, the 

 papillary muscles, etc., as in the case of the right side of the heart 

 (12). 



d. Examine the semilunar valves at the exit of the aorta; then cut- 

 ting up carefully between two of them, examine the bit of aorta still 

 left attached to the heart, and note the valves more carefully as de- 

 scribed in 12, d. 



14. Examine a piece of aorta. Note that when empty it does not 

 collapse; the thickness of its wall; its extensibility in all directions; 

 its elasticity. 



^5. Compare with the artery the thin-walled flabby veins which 

 open into the heart. 



