48 THE FROG 



302, The matrix, a lightly stained mass (transparent in 

 life) with spaces, lacunae, in which the cells appear. 



303. The perichondrium, a layer of connective tissue 

 with small blood vessels, covering the cartilage. 



Drawing 25. Draw a section showing all structures 

 mentioned above, 



8. Bone (Transverse Section op Femur, Decalcified) 



In the slide provided^ note the following: 



304. The periosteum, a layer of connective tissue, re- 

 sembling the perichondrium (303). 



305, The outer zone of compact bone. Study with high 

 power and observe 



306 the irregularly star-shaped bone cells. 



307. The matrix with its concentric layers, the laminae, 

 the lacunae surrounding the cells, the widely branch- 

 ing delicate canals leading from them, the canaliculi. 

 Sometimes the cells are grouped around cavities con- 

 taining blood vessels and nerves. These cavities are 

 called Haversian canals. 



308. The bone marrow, forming the center of the femur. 

 It is essentially an adipose connective tissue with 

 many blood corpuscles. Examine under high power. 



Drawing 26. Draw in outline the entire section. Fill 

 in the details in a narrow sector only. 



4. Striated Muscle. (Longitudinal Section) 



In the slide loaned you, identify: 



309. The muscle cells or fibers. They are grouped in 

 bundles or fasciculi. Study under high power and 

 note in each fiber several nuclei, longitudinal stria- 

 tions (sarcostyles), transverse striations (dividing 



