50 



97- Developing tooth ; later stage. Dog. Transection 

 through the lower jaw of a new born puppy. Picric alcohol ; decal- 

 cified (§ 131) ; collodion ; sections pi. Stain with hematoxy- 

 lin and picrofuchsin. 



Be sure your section passes through a developing tooth. In 

 this more mature tooth there should be recognized (a) the enamel 

 organ with its three layers, (d) the enamel, {c) the dentine lined 

 by the odontoblasts, and finally (d), the dental pulp, containing 

 blood vessels. 



98. Tongue. Rabbit. Transection. Miiller's fluid ; stained 

 in Mo (§ 74 c) ; collodion ; sections pi. 



Study the preparation, noting the surface epithelium with low 

 papillae, in the body of the tongue, the mesal septum and the bun- 

 dles of muscle in general running vertically, longitudinally and 

 transversely ; also nerves and blood vessels. 



ESOPHAGUS. 



99. Esophagus. Dog. Transection. ; 

 sections /j.. Stained hi toto. 



In this preparation, as well as in the succeeding regions of the 

 digestive tract, identify the four coats — mucosa, submucosa, (inner 

 and outer) muscular and serous coats. In the mucosa and sub- 

 mucosa observe the character of the lining epithelium, the mucous 

 glands ; find if possible a duct opening upon the lining epithelium ; 

 the muscularis mucosa ; the character and direction of its fibers. In 

 the muscular coats determine the character and direction of the 

 muscle fibers. What differences are there in diflferent animals in 

 the muscular coats of the esophagus ? 



100. Esophagus. Homo or sheep. Assigned for study. 

 Transection. 



Compare with 99, recognizing the coats, the epithelium, mus- 

 cularis mucosa, character and relation of the muscular fibers in the 

 muscular coat. Are glands present ? 



STOMACH. 



loi. Stomach. Dog. Vertical section of the wall, cardiac 

 end near the esophagus. ; collodion ; section ft. 



Stain the sections with hematoxylin and eosin. 



