INTRODUCTION. 5 



substances that are kept warm and moist. Fresh bread kept 

 moist and covered with a glass will in a short time produce a 

 varied crop of moulds, and fresh horse manure kept in the 

 same way serves to support a still greater number of fungi. 



Mosses, ferns, etc., can be raised with a little care, and of 

 course very many flowering plants are readily grown in pots. 



Most of the smaller parasitic fungi (rusts, mildews, etc.) 

 may be kept dry for any length of time, and on moistening 

 with a weak solution of caustic potash will serve nearly as 

 well as freshly gathered specimens for most purposes. 



When it is desired to preserve as perfectly as possible the 

 more delicate plant structures for future study, strong alcohol 

 is the best and most convenient preserving agent. Except for 

 loss of color it preserves nearly all plant tissues perfectly. 



