364 ESSENTIALS OF BOTANY 
BIBLIOGRAPHY 
In this place only a few suggestions will be given to supplement 
the bibliography of the Mgnual. The books which are there double- 
starred are among the most important for reference. Some, how- 
ever, like Pfetfer’s Physiology of Planis, are very expensive, and such 
briefer works as Peirce’s Text-Book of Plant Physiology (Henry Holt & 
Co., New York), or Green’s Introduction to Vegetable Physiology (P. 
Blakiston’s Sons & Co., Philadelphia), may be bought as an alter- 
native. It is often found difficult to identify even the genera of alge 
and fungi which are encountered in collecting. For fresh-water 
algee and some aquatic fungi no book is more useful than Whipple’s 
Microscopy of Drinking Water (John Wiley & Sons, New York). 
Many fungi can be identified by means of Massee’s Text-Book of 
Fungi (The Macmillan Company, New York). 
SPECIAL TOPICS FOR STUDY 
Economic Botany. — Few subjects will be found to interest most 
classes more than some of the topics of economic botany. These 
can often be assigned for optional work, for which credit may be 
given. The topics to be suggested would vary much, according to the 
environment of the school. In agricultural districts reports on local 
conditions as regards use of improved seed for farm and garden 
crops, on trials of new economic plants, on tree-planting and the 
management of wood lots, would all prove valuable subjects for 
discussion. City high-school classes can find fewer opportunities 
for reports and investigations, but some practicable topics are the 
comparative value of various species of shade trees and the insect 
enemies of each species, the sources of the winter flower-supply and 
modes of forcing flowers, the examination of the gross and histological 
characteristics of woods and the classification of these by families 
and according to their structural likenesses, the study of commer- 
cial fibers, the histological examination of vegetable foods (such as 
starches) and of powdered drugs. Many interesting and valuable 
studies of the relation of microscopic organisms to fermentation and 
decay may be made with simple apparatus, as described in Conn’s 
Bacteria, Yeasts, and Molds in the Home (Ginn & Company). 
