PRACTICAL DIRECTIONS. 453 



the larynx (p. 249, and Fig. 105). Dissect all those of one side 

 first. The mucosa lining the vestibule and middle portions of the 

 laryngeal cavity must be removed. After studying the muscles, 

 remove the muscles and entire mucosa by scraping carefully with a 

 dull but smooth scalpel, and study the cartilages (Fig. 104). 



III. The trachea and lungs (p. 251, and Fig. 106). The distal 

 end of the trachea and lungs may now be removed with the heart 

 from the body. The lungs may be inflated with the bellows. The 

 bronchi should then be exposed, cleaned, and followed as far as 

 possible into the lungs. The heart should be preserved for future 

 study. 



DISSECTION OF THE UROGENITAL ORGANS. 



A. Excretory Organs. 



1. Expose the kidney (p. 255, and Fig. 108) by removal of the 

 peritoneum and the surrounding fat, taking care not to open the 

 capsule of the kidney. In removing the fat from the cranial end do 

 not injure the suprarenal body (p. 257), which should be studied. 



2. Open the capsule of the kidney and slice away its ventral wall 

 to expose the sinus. After dissecting the contents of the sinus open 

 the pelvis and study the papilla. Pass a bristle from the pelvis into 

 the ureter. 



3. Make a median section of the kidney parallel to its ventral 

 surface and study structure (Fig. 109). 



4. Trace the ureter to the bladder, being careful not to injure 

 the vas deferens. Study the bladder and its ligaments, structure of 

 its wall, etc. Pass a bristle through the ureter into it and then open 

 it to see the openings of the ureter. Trace the neck of the bladder to 

 the pubis. 



B. Male Genital Organs. 



1. Study the external genital organs (p. 257). 



2. Carefully remove the integument about the anus and expose 

 the external sphincter ani muscle (p. 268, and Fig. 113, *'). Trace 

 it to its origin. Remove the integument of the scrotum and dissect 

 the intercolumnar fascia, the levator scroti muscle (p. 271, and Fig. 

 113,7), tne tunica vaginalis communis, and propria (p. 258). 



3. The testis; the epididymis with great care,, especially in 

 uncovering the vasa efferentia; the vas deferens and spermatic cord 

 (p. 259, and Figs, no and in). 



4. Follow the cord to the external inguinal ring (p. 259) and 

 expose the ring. Dissect off in order from the inguinal canal : (a) 

 The external oblique muscle; (b} the internal oblique muscle; (c) 

 the transversus. In this way the cord is followed with its tunica 

 communis and tunica propria to the internal inguinal ring. 



5. Trace the vas deferens (p. 260, and Fig. in) within the 

 abdominal cavity as far as it can be seen dorsad of the neck of the 

 bladder. 



