140 BOTANY. 



hrella-shapecl bodies on the upper surface. Note that the expanded part 

 of this umbrella-shaped structure is crenate on the margin, giving it a lobed 

 appearance, and that these lobes radiate from the centre. Search for 

 little pits opening on the upper surface of these structures ; these are the 

 opening of the chambers where the antheridia are borne. With a hand lens 

 examine the upper surface of the thallus. Can you see that it is marked off 

 into diamond-shaped areas, with a minute opening in the centre of each ? 

 These openings are the stomates of the thallus. Observe that the central 

 line of the thallus is thicker than the margins. This is the midrib. 



Exercise 48. 



232. Female plants. Study these in a similar way, and compare. The 

 thallus is very similar, the greater point of difference being in the umbrella- 

 shaped structures. Note that the expanded portion is more deeply lobed, 

 forming prominent rays. On the under surface observe the delicate hanging 

 fringes. Underneath these the archegonia are borne. If material with ripe 

 fruit is at hand preserved in formalin, observe the rounded capsules on short 

 stalks which protrude from beneath these curtains. Sketch and describe all 

 parts of the plant. 



Exercise 49. 



233. Sterile plants bearing cups and gemmae. Study these in a similar 

 way. Note that the umbrella-shaped structures are absent. Observe the 

 minute cups on the upper surface. With a hand lens note the minute flat- 

 tened green bodies within the cups. These are the gemmae, or buds, and 

 serve as one means of propagating the plant. 



Demonstration 35. 



( May be omitted. ) 



234. Sexual organs. The teacher may make demonstrations to show the 

 sexual organs, and the spores and elaters. For the antheridia section the 

 antheridial receptacle, and for the archegonia section the archegonial recep- 

 tacle. Unless one is familiar with methods of sectioning these structures, it 

 would be better to purchase prepared sections of these organs for the demon- 

 stration. See fig. 123. 



Demonstration 36. 



235. Spores and elaters. When the fruit is ripe (see fig. 125) and the 

 spores and elaters are escaping some may be mounted. They may be 

 mounted in glycerine jelly. Such mounts will keep for a long time if cared 



