76 GENERAL BIOLOGY. 



specimens), and the subepidermis : a 

 conspicuous brown layer. 



(b) Next to this a region of nearly colorless 



cells. Compare these with (a) in regard 

 to cell-contents and thickness of cell- 

 wall. 



(c) In the centre a central or axial strand. 

 Make a diagram showing the outlines of the different 



regions. Sketch a few cells of each kind to show 

 tlieir characteristics. 



Make a longitudinal section, mount in ivater and 

 find the same regions. Sketch carefully to the 

 same scale a few cells of each kind. 



2. Leaf. 



Mount in water a young leaf of a more delicate 

 species of moss as Mnium and study with D 2 

 to see : 



(a) The structure, a thin lamina with a thicker 



median region, the midrib. 



(b) The margin of the lamina. 



Sketch two or three cells at the edge of the leaf to 

 show the character of the margin. 



3. Ehizoids. 



Mount in water. With D 2 note : 



(a) Cell-contents. 



(b) Any difference that is observable between 



the younger and the older rhizoids. 

 Sketch. 



4. Reproduction. 



