50 THE FROG 



318. the stratum germinativum (Malpighii), columnar 

 epithelium, below the corneum. 



319. The dermis (cerium) underlies the epidermis and is 

 connective tissue. Like the epidermis it is divided 

 into two layers, 



320. the stratum spongiosum, towards the exterior, which 

 is a loose layer containing the dermal glands (323), 

 and the pigment cells (chromatophores), and 



321. the stratum compactum beneath containing both 

 white and yellow fibers, some smooth muscle cells, 

 blood vessels and nerves. 



322. Beneath the dermis is the sub-cutaneous layer of 

 connective tissue which connects the skin with the 

 muscles of the body wall. This is a loose connective 

 tissue, divided into two layers by the lymph spaces. 



323. The glands are of two types, the more frequent and 

 smaller mucous glands and the relatively rarer and 

 larger poison glands. The glands are composed of 

 a layer of epithelial secretory cells, surrounded by a 

 layer of smooth muscle cells, which in turn is covered 

 with fibrous connective tissue. Each gland com- 

 municates with the exterior by a duct whose aper- 

 ture is called a stoma. 



Drawing 29. Draw a section of skin to show as many 

 of these structures as possible. 



7. The Intestine (Transverse Section of Ileum) 



In the section provided, locate the following structures: 



324. The interior of the tube is lined by the mucosa, 

 which is secretory columnar epithelium. Under high 

 power distinguish the goblet cells which have an 

 oval vacuole filled with mucus at the inner end. 



325. Exterior to the mucosa lies the submucosa, an ex- 



