150 DRA WING WITH THE MICROSCOPE [ CH. V 



scopic object is very distinct and the pencil is invisible or very in- 

 distinct. If the drawing surface is too brilliantly lighted the pencil 

 can be seen clearly, but the microscopic image is obscure. 



When opaque objects, that is objects which must be lighted 

 with reflected light ( § 72), like dark colored insects, etc., are to be 

 drawn the light must usually be concentrated upon the object in 

 some way. The microscope may be placed in a very strong light 

 and the drawing board shaded or the light may be concentrated upon 

 the object by means of a concave mirror or a bull's eye condenser 

 (Fig. 60). 



If the drawing surface is too brilliantly illuminated, it may be 

 shaded by placing a book or a ground glass screen between it and 

 the window, also by putting one or more smoked glasses in the path 

 of the rays from the mirror (Fig. 124 G). If the light in the mi- 

 croscope is too intense, it may be lessened by using white paper 

 over the mirror, or by a ground glass screen between the microscope 

 mirror and the source of light (Piersol, Amer. M. M. Jour., 1888, 

 p. 103). It is also an excellent plan to blacken the end of the draw- 

 ing pencil with carbon ink. Sometimes it is easier to draw on a 

 black surface, using a white pencil or style. The carbon paper 

 used in manifolding letters, etc., may be used, or ordinary black 

 paper may be lightly rubbed on one side with a moderately soft lead 

 pencil. Place the black paper over white paper and trace the out- 

 lines with a pointed style of ivory or bone. A corresponding dark 

 line will appear on the white paper beneath. ( Jour. Roy. Micr. Soc. , 

 1883, p. 423). 



(A) It is desirable to have the drawing paper fastened with 

 thumb tacks, or in some other way. (B) The lines made while 

 using the camera lucida should be very light, as they are liable to 

 be irregular. (C) Only outlines are drawn and parts located with 

 a camera lucida. Details are put in free-hand. (D) It is some- 

 times desirable to draw the outline of an object with a moderate 

 power and add the details with a higher power. If this is done it 

 should always be clearly stated. It is advisable to do this only 

 with objects in which the same structure is many times duplicated, 

 as a nerve or a muscle. In such an object all the different struc- 

 tures can be shown, and by omitting some of the fibers the others 

 may be made plainer without an undesirable enlargement of the 

 entire figure. 



