238 APPENDIX 



■with spores from an old culture. These small cultures can be readily- 

 handled and studied with the hand lens, especially portions of the 

 mycelium which may grow out over the surface of the watch glass. 

 The bread mold is almost invariably followed by extensive growths of 

 the green mildew, Penicillium. 



16. Lichens. When time is limited it is more important that the 

 lichen be studied than such Ascomycetes as Microsphcera or Peziza, since 

 most lichens show excellently the fruiting characters of the sac fungi. 

 The remarkable associations of fungi and algae to form these composite 

 organisms gives the lichens peculiar interest. A variety of lichens 

 should be collected, dried, and fastened to cards for comparative studies 

 of growth habits and form. 



17. Gill fungi. The study of gill fungi must frequently be made at 

 times inconvenient or impossible for field trips. The laboratory work 

 may then be upon material preserved in strong alcohol or on edible 

 forms sold in the markets (the commonest is Agaricus campestris). 

 Horse manure placed under a bell jar will give excellent material of 

 some small and delicate species of Coprinus, the development of which 

 will prove interesting. 



18. Diagrams and formuls illustrating alternation of generations. The 

 dilRcult subject of alternation of generations may generally be made 

 clearer if the chief phases in the life histories of the types studied are 

 represented by a series of diagrams. It is helpful if the diagrams are 

 drawn with colored pencils ; thus the gametophyte phases may be rep- 

 resented in yellow and the sporophyte phases in green. Life-history 

 formulae may b6 constructed after the manner suggested in the Princi- 

 ples, pp. 222, 278, 319, 336, and 375. 



19. Mosses. Field studies of the mosses may not be possible at the 

 time the type is studied in the laboratory. However, dried material is 

 generally very satisfactory for habit studies on a variety of forms, and 

 the greenhouses and cultures (Sec. 207) may be depended upon to fur- 

 nish living material. Moss spores will generally germinate in sweetened 

 water. 



20. Ferns. A variety of ferns may be easily cultivated in the labora- 

 tory, which with herbarium material will give a very good idea of dif- 

 ferent forms of stems and leaves. A simple study of stem structure may 



. be made by cutting across stems and whittling them lengthwise. Such 

 an examination will make clear at least the position and importance 



