192 METHODS IN PLANT HISTOLOGY 



If one should need a line drawing of a tree, or flower, or mushroom, 

 a kind of drawing that, ordinarily, requires real artistic ability, there is 

 a way to get an outline with as good proportion and perspective as 

 even the best artist could not surpass. Photograph the object, make 

 a lantern slide, and then throw the object on cardboard and trace 

 with a pencil. It is more convenient to catch the object on a mirror 

 placed at 45° and thus throw the object on the cardboard resting on 

 the table. Drawings can be made from photomicrographs in the same 

 way. Instruments can be bought which will throw the object down di- 

 rectly, saving a lot of time in many cases. However, the projection 

 method is not as slow as it seems and it is not expensive, since lantern 

 slide plates can be used. By projecting upon durable cloth, very effi- 

 cient charts can be made in this way. 



The lithograph is so expensive that it has almost disappeared from 

 botanical journals, except in countries where labor is cheap. This type 

 of illustration is still furnished to those who are fortunate enough to 

 get grants from Foundations. The copy may be in pencil or in ink or 

 in a combination of pencil, ink, and washes. If your copy is poor, ex- 

 plain to the lithographer how you want it and he can fix it for you. 



A photolithograph is excellent, better than a lithograph, if you can 

 draw better than the lithographer; but not so good as a lithograph, if 

 the lithographer is your superior. The photolithograph is rather ex- 

 pensive; consequently, journals which are having a hard time to live 

 within the budget look with disfavor upon anything more expensive 

 than the zinc etching and the halftone. The copy for a photolitho- 

 graph should not be a mixture of pen and pencil work, but should be 

 all in pencil or all in ink. To get different shades with ink, dilute the 

 ink for lighter tones: do not use a pencil. The best reproductions by 

 the photolithographic method are made from copy entirely in dead 

 black ink on pure white cardboard, different shades from light to dark 

 being obtained by dots and lines. Such a photolithograph can be 

 printed in a lithograph colored ink, and the finished product looks like 

 an expensive genuine lithograph. 



Photographs of trees, flowers, and landscapes are nearly always re- 

 produced by the halftone process. Remember that there is a screen 

 which makes black lines through light parts and light lines, through 

 black parts, thus reducing the contrasts so that a good print from a 

 good negative will be disappointing. This may be remedied, to some 

 extent, by using a contrasty plate or film, and a contrasty developer 



