NEGATIVE MAKING 65 



red a highly non-actinic color the amplifi- 

 cation is some three times greater than before 

 and the rays of light have to pass through an 

 ocular which always diminishes their intensity 

 in a large degree. Clearly we must allow them 

 considerably more time in which to do their 

 work, say three times. So we give 30 seconds 

 exposure, and upon treatment with the pre- 

 viously used developer find we have an excel- 

 lent negative from which the reproduction 

 (Fig. 7) has been made. 



For the benefit of some entomological 

 friends who will probably be among my readers, 

 we will make one more negative with a low 

 power; choosing, this time, that ever favorite 

 subject, u the blow-fly's tongue," which pre- 

 sents in its suctorial tubes one of the best 

 tests for a half to one inch objective that I 

 know of. We will use the same optical 

 arrangement as that in the last example, ex- 

 cepting the objective, for which I have substi- 

 tuted one of same power f by Ross. The 

 plate is a Wuestner orthochromatic ; the screen 

 dark yellowish-green pot-glass, the radiant 

 acetylene. Exposure, 30 seconds; developer, 

 hydroquinone. You see the reproduction in 

 Fig. 8. Observe how beautifully the tubes or 

 false trachea are delineated. 



