NEGATIVE MAKING 



79 



ject by a bull's-eye condenser; plate, rapid 

 landscape; exposure, 30 seconds; developer, 

 eiko-hydro; magnified 53 diameters. Fig. 16: 

 Objective, Beck's first-class i%-inch; ocular, 

 none ; radiant, diffused daylight falling upon 

 object, the camera being used in upright po- 

 sition; plate, rapid landscape; exposure, ten 

 minutes, this apparently excessive time being 

 rendered necessary by the color of object 

 bright yellow on green background and the 

 dimness of illumination; developer, same as 

 preceding; amplification, 30 diameters. Mdd- 

 ium grossularia ; cluster cups. 



Polarized Light. It is a matter of regret 

 to me, at least that this method of illumi- 

 nation has fallen into such general neglect, 

 and that its beautiful effects and valuable 

 aid in the delineation of very many struc- 

 tures are utterly unknown to the majority of 

 students at this day. A generation since, every 

 microscope was supplied with polarizing ap- 

 paratus almost as carefully as it was with ob- 

 ject glasses. Now probably not one student's 

 stand in a thousand can boast of one. None 

 the less, the beauties it reveals may be opened 

 by no other key, and I confidently predict that 

 this formerly indispensable adjunct to a com- 

 plete microscopical outfit will again become 



