36 LABORATORY PRACTICE CHAP. VI. 



IX. Examine a piece of the so-called Smilax (Myrsiphyl- 

 lutri) and notice : 



1 . The slender stem. 



2. The expanded leaf-like structures. Notice their shape 



and venation. 



3. The delicate scale at the base of each of these leaf-like 



structures. This scale is the true leaf, and the ex- 

 panded structure in its axil (see I, 7, of Chapter V) 

 is a branch flattened to serve as a leaf. A branch 

 structure modified thus is called a cladophyllum 

 (plural is cladophylla) . 



4. Make a sketch of one cladophyllum, its subtending scale- 



like ka/a.nd the piece of. stem upon which it is borne. 



X. Examine some plants which have been grown before 

 a window (and consequently strongly lighted from one side) . 

 Notice : 



1. That the leaves present their upper surfaces to the light. 



2. Turn the plants around and notice, after a day or two, 



that the leaves have turned so that their upper 

 surfaces are again directed toward the light. 



XI. Examine a plant of some species of Oxalis and 

 notice : 



1. The trifoliate, palmately compound leaves. 



2. The position of the leaflets during the day-time. 



3. The position of the leaflets during the night-time. 



4. Sketch both positions. 



5. What causes the so-called " sleep " of plants? 



XII. Examine a Sensitive Plant and notice : 



i. The character of the expanded undisturbed leaf. Sketch. 



