306 THE BIOLOGY OF THE PLANT 



another vertical section passing through the pi- 

 leus to one side of the stipe and through the gills 

 in such a way as to divide the latter transversely. 

 Examine under the low power. How are the 

 lamellae attached to the pileus? Do their "tis- 

 sues" seem to be continuous ? Draw. Examine 

 under the high power. Endeavor to make out 

 the central portion, or trama, the sub-hyme- 

 nial layer, and the outer portion, or hymenial 

 layer, of each giU. What is the structure of the 

 trama? In what ways does it differ from the 

 central part of the stipe and the pileus ? What 

 is the course of the hyphse? How do you distin- 

 guish the sub-hymenial layer ? How do its ceUs 

 differ from those of the trama? What is the 

 structure of the hymenial layer? What is the 

 direction of its cells ? Are they continuous with 

 those of the next layer below ? Study this layer 

 closely, and endeavor to make out that it consists 

 of two kinds of cells, those with rounded ends, 

 the paraphyses, and the basidia, ending in two 

 pointed processes or sterigmata. How are the 

 paraphyses and basidia arranged with regard to 

 each other ? Can you think of any use which the 

 former may have ? How do they differ in shape ? 

 ISTote the rounded body, the basidiospore, 

 borne by each sterigma. Examine sections from 

 young mushrooms to find the paraphyses, basidia, 

 and spores in various stages of development. Note 

 how the sterigma and its spore are formed. Make 

 a diagram showing the arrangement of the tissues 

 of the lamella. Draw several isolated paraphyses 

 and basidia. 

 Break off the pileus of a mushroom whose 



