THE DRAWING OF MICROSCOPIC OBJECTS. 301 



heighten the realistic execution of the drawing, that it may almost 

 be mistaken for the microscopic image. 



The opposite process of delineation by which the brightest spots 

 are regarded as the darkest, and vice versa would be of equal value 

 for scientific purposes. a j 



But, just as in chart- 

 ography, the process 

 resolves itself to this 

 that the drawing must 

 be executed according 

 to a certain system, 

 whatever may be de- 

 cided upon. The sec- 

 tion of a cylindrical 



cell, the membrane of which consists of two dense outer layers 

 and one less dense (red) layer, may consequently be just as well 

 represented by Fig. 168 b as by Fig. 168 a. Generally speaking, 

 a white background is more serviceable where the multiplication 

 of the diagram is contemplated, and is attended with other prac- 

 tical advantages also. 



If, in accordance with these explanations, we now examine the 

 anatomical figures given in the more .recent works on the subject, 

 we shall at once perceive that neither the one principle nor the 

 other has been strictly adhered to. Most draughtsmen (we do not 

 exclude even ourselves) commence work, consciously or uncon- 

 sciously, in an intentionally eclectic manner ; for instance, they re- 

 present thick cell- walls by light tints, while they represent thread- 

 like concretions, and the starch-grains contained in the lumen, &c. r 

 by dark tints. Everyone who will carefully examine finished ana- 

 tomical drawings with reference to the method of representation 

 will almost always meet with these incongruities. As an example 

 we will just mention the elegant plates of Schacht's " Lehrbuch der 

 Anatomie und Physiologic." It contains many figures which at 

 first sight might seem to be very perfect drawings, but which on 

 closer examination turn out to be. mere outlines, in which the most 

 arbitrary shading serves to direct attention to certain parts of 

 them. The concentric circles, by which, for instance, the strati- 

 fication of bast-cells is indicated (Plate V., 3), correspond neither 

 to the looser nor to the denser layers ; for if we were to assume that 

 this were the case, then the relative thicknesses of the two layers 



