106 



PHOTOGRAPHING BACTERIA. 



When a colored screen is used this may be placed either before 

 or behind the condensing lens we prefer to place it behind, although 



Neuhauss has shown that it makes no difference in the length of th< 

 exposure. 



\\ 6 <Miin.)t iii tin- pivsimt volume iciv> full d.'tails with ivtVivmv 



