88 ELEMENTARY PHOTO-MICROGRAPHY. 



JIN. OBJECTIVE. 



Transmitted 

 Light. 



Section of Deal. " A " eyepiece. Rapid plate. Ten 

 minutes. 



OBJECTIVE. 



Transmitted 

 Light. 



Human Blood. " A " eyepiece. Chromatic plate. Green 

 colour screen. Thirty-five minutes. 



. OIL IMMERSION. 



Transmitted j Bacteria. Stained red. " A " eyepiece. No colour screen. 



Light. 



Chromatic backed plate. Twelve minutes. 

 Ditto, with green colour screen. Thirty minutes. 



* INSTANTANEOUS EXPOSURE IN PHOTO- 

 MICROGRAPHY. 



Although flashlight has been in common use for 

 purposes of ordinary photography, it has not been 

 tried within the writer's knowledge for photo- 

 graphing through the microscope ; but, in the 

 absence of a powerful illuminant, such as the 

 electric light, a ready and simple substitute can 

 be provided whenever the exposure of a fractional 

 part of a second is needed. 



In preparing illustrations of pond life, for 

 example, preference is given to dead specimens 

 mounted without pressure, for the simple reason 

 that a time exposure is impossible with anything 



* Paper read before the Royal Microscopical Society, October i8th, 1911. 



