15° BOTANY. 



Among the material search for those capsules representing several different 

 ages. Very young ones are often collected when there appears to be nothing 

 but a slender stalk, the capsule not yet being fully developed. Search on the 

 capsule for the hairy hood, known as a calyptra. Remove this ; note its form. 

 Now at the end of the capsule note the conic lid (the operculum). Remove 

 this, or examine older capsules where the lid has fallen away. Note the 

 numerous teeth. When the lid is removed, are there any small granules 

 (the spores) escaping ? Compare the shape of the capsules of different ages. 



Exercise 5 1 . 



245. The male plants Note the broad rosette of leaves at the end of the 



stem. Compare the arrangement of the leaves here with those lower down 

 on the stem. Sketch. The antheridia (sing, antheridium) are borne in the 

 centre of the rosette. 



246. The female plants. — Compare with the male plants : what is the 

 difference in the arrangement of the leaves? Can you suggest why the 

 leaves are arranged differently in the two plants ? 



Demonstration 37. 



(May be omitted when necessary. ) 



247. Demonstration of spores, etc. — The teacher can prepare mounts of 

 the spores, and of a portion of the mouth (peristome) of the capsule for study. 

 If it is desired also leaves may be examined under the microscope. The 

 leaves are made up of a single layer of cells, except at the middle line where 

 the cells are several layers thick, and long and narrow. The cells in the 

 middle line form the "midrib" of the leaf. The teacher can also make 

 sections through the ends of the male and female plants to demonstrate the 

 sexual organs, or prepared slides representing these may be purchased for 

 demonstration. 



Description of the Moss, Mnium. 



248. Mnium. — We will select here the plant shown in fig. 

 128. This is known as a mnium (M. affine), and one or 

 another of the species of mnium can be obtained without much 

 difficulty. The mosses, as we have already learned, possess an 

 axis (stem) and leaf-like expansions, so that they are leafy- 

 stemmed plants. Certain of the branches of the mnium stand 

 upright, or nearly so, and the leaves are all of the same 

 size at any given point on the stem, as seen in the figure, 



