96 THE TEACHING BOTANIST 



are living plants growing untouched in their native 

 homes. But practically the use of these* is very limited, 

 for some of the most instructive are tropical or of other 

 lands, and the native ones are not only often distant, 

 especially from students in cities, but in our climate are 

 unavailable for most of the school year. These draw- 

 backs are partially overcome by botanic gardens, which 

 not only bring plants together from the uttermost parts 

 of the earth, but group them in a manner which is itself 

 instructive. Plants in gardens, however, while valuable 

 for investigations upon structure and classification, are 

 nearly valueless for studies upon their natural relations 

 to their surroundings, though they may be so grouped 

 as to form valuable illustrations of some well-known 

 principles of ecology. The teacher who is so fortunate 

 as to be within reach of a botanic garden should make 

 the acquaintance of the director and obtain permission 

 for himself and his students to use it freely, which will 

 usually be readily granted. Botanic gardens are very 

 numerous in Europe, but rarer in this country ; the 

 principal ones of North America are the following, 

 arranged in order from east to west : 



The Arnold Arboretum (a department of Harvard 

 University), at Jamaica Plain, Mass. 



The Botanic Garden of Harvard University, at Cam- 

 bridge, Mass. 



The Botanic Garden of Smith College, at North- 

 ampton, Mass. 



