386 APPENDIX. 



an arrangement to burst the sporangium when mature. (Fig. 

 238.) 



Breathe on the dry mass of spores. Watch the squirming 

 movements. 



12. Demonstration. Mount a few spores in water and others 

 dry, and show the elaters ; strips of the outer walls of spores, 

 loosened but wrapped around spores when moist, straightened 

 out when dry. (Fig. 239.) 



Examine the green branched shoots (fig. 235, B). Compare struc- 

 ture with other shoots, noting differences. Observe 



13. Profuse branching and the arrangement of the branches and 

 branchlets. 



14. Cut a longitudinal section through the base of a branch. 

 Observe that the branches arise from the stem above the origin 

 of leaves and burst through the sheath. 



15. That the nutritive work depends on the stem, not on the 

 leaves, which lack green tissue. 



16. The roughness of the surface. Rub branches on a metal 

 surface and observe that they scratch it, on account of silica in 

 walls of surface cells. 



C. SELAGINELLA (.V. rupestris). 



I. Gametophytes, male and female, are extremely reduced, 

 scarcely bursting the wall of the spores producing them. See 



IT! 384. 392, figs. 315, 333. 



II. Sporophyte. 



Examine in water an entire plant. (If previously dry it should 

 be boiled for a few minutes in water.) Observe 



1. The yellow thread-like secondary roots arising at various 

 points from the stem. (Structure like fern.) 



2. The branched shoots; note method ; lateral branches arising 

 from side of mother shoot, i.e., monopodial branching. 



3. The crowded foliage leaves. Mow arranged ? (See p. 97.) 



4. The sporophylls. Search for ends of branches having leaves 

 in four vertical ranks. Compare form of these leaves with foliage 

 leaves. Observe 



5. In their axils large yellow sacs, the sporangia ; some con- 

 taining 



6. One to three large spores, the megaspores; more abundant 

 than similar sporangia containing 



