800 DIRECTIONS FOE LABORATORY WORK 



also in the colon the haustra, the plicae semilunares and the appendices 

 epiploica?. Sketch l.p. (260). 



(L) RECTUM. 



Sketch l.p. (261) the area of transition from the rectum to the anus 

 to show the structural differences in the several tunics. Compare the 

 rectum with the colon. Enumerate the grosser differential marks among 

 colon, appendix and rectum. Note rectal valves, rectal columns, and 

 anal valves. 



Study an injected specimen of the small intestine of the cat. Sketch 

 the blood supply of a villus and of a crypt of Lieberkiihn (262). 



XV. THE LARGE GLANDS OF THE DIGESTIVE CANAL 



(A) THE LARGER SALIVARY GLANDS. 



(1) THE PAROTID GLAND. Study under the low power of the micro- 

 scope a stained section of the parotid gland. Sketch (263), show-' 

 ing the division into lobes and lobules, and the location of the inter- 

 lobular and intralobular excretory ducts. Note the distinction between 

 the parenchyma and the stroma or interstitial tissue. 



Sketch 'h.p. (264) an alveolus (acinus) in connection with its inter- 

 calary duct. Note the shape, manner of distribution within the alveolus, 

 stage of secretion as indicated by the cytology, staining reaction and 

 relation to the 'basket cells' of the constituent secretory cells of the 

 acinus. Sketch h.p. (265) also transverse sections of the secretory (sal- 

 ivary) and the excretory portions of the intralobular duct. 



(2) THE SUBLINGUAL GLAND. Study a stained section of the 

 chief sublingual gland (of man, dog, cat or rabbit). Sketch h.p. (266) 

 an alveolus with a large demilune ( f crescent' of Gianuzzi). Explain the 

 functional significance of the difference in staining reaction between the 

 cells lining the alveolus and those of the demilune. Probable function 

 of the demilune cells? Chief difference in duct systems of parotid and 

 sublingual glands? 



(3) THE SUBMAXILLARY GLAND. Compare the submaxillary 

 with the parotid and sublingual glands. Enumerate the chief differen- 

 tial characteristics among these three glands. Sketch h.p. (267) two 

 adjacent alveoli, one of the mucous the other of the serous type. From 

 an injected specimen of cat's submaxillary gland sketch (268) the intra- 



