THE FUNGI 257 



which all of the books tell about ; Yeast, of course, from 

 yeast-cake placed overnight in water with a little sugar (Yeast 

 may be made to form spores by growing on plaster of Paris 

 plates as described in books) ; Bread Mould by keeping bread 

 several days moist in a warm place ; Mushrooms from the mar- 

 kets, or canned, may be used. Of course, there are numerous 

 other easily available forms of Fungi that may be used if time 

 allows, but it is most important to use the chief types. 



Pedagogics. As under Algae. A full account of economics 

 should be given in lectures or demonstration, including the 

 importance of Bacteria not only in decay, diseases, etc., but 

 in the arts (cheese-making, etc.), the nitrification of soils, 

 fixation of nitrogen in Leguminosse, etc. Full descriptions 

 should be given also of the important forms of Mildews, Rusts, 

 and others of economic importance ; those which are studied 

 in the laboratory will form a good basis for the theoretical 

 study of others, for each form actually studied by the student 

 illuminates many others. 



If the material on any particular stage is insufficient, dia- 

 grams may be copied ; this is better than skipping an impor- 

 tant stage altogether. 



It is especially important to keep constantly prominent 

 the place-in-natitre-and-among-other-plants idea, which requires 

 generalization and active use of the imagination. 



Very important is the phylogenetic relationship of one of 

 these groups to another : the teacher should make it plain 

 that Fungi are forms degenerate through parasitism from the 

 Algae, and not a homogeneous group, but derived from dif- 

 ferent sub-groups of the Algae (see Fig. 29). There is great 

 difference of opinion as to the details of the relationships of 

 these groups. There is a valuable discussion of the subject in 

 Campbell's " Evolution of Plants." 

 s 



