114 THE TEACHING BOTANIST 



work " Pflanzengeographie," on which further informa- 

 tion is given in the next chapter. Large photographs 

 of microscopic sections have some value, and an un- 

 usually fine series, by Tower, is sold by Ginn and 

 Company, Boston. 



After photographs, and for some purposes before 

 them, come drawings or diagrams, which are of two 

 general sorts, those intended to show the very living 

 appearance of plants or their parts, including enlarged 

 views of small organisms, and those intended merely to 

 help to a vivid vizualization of their structure. The 

 former are not of much value unless very well done, 

 true in perspective, and correct in coloring ; indeed, it 

 may be said their value is in direct proportion to their 

 artistic excellence. Good examples occur among the 

 diagrams of Kny, Dodel, and Peter, to be mentioned 

 below. Not much can be done toward making home- 

 made diagrams of this kind unless an artist is available. 

 In the second kind, however, those to simply help the 

 mind to form a three-dimensioned conception of some 

 complicated structure, the element of objective correct- 

 ness is not so important ; and of such diagrams I think 

 the very best is that which grows before the student's 

 eyes on a blackboard under the hands of a teacher, with 

 copious explanation and the aid of colored crayons, etc. 

 Some skill in blackboard drawing is very desirable in 

 the teacher, and I have no doubt that in time the in- 

 creasing care devoted to the education of teachers of 



