22 PHOTOMICROGRAPHY 



and metal dark slide (Fig. 9). In the opposite end of the 

 box a hole was drilled, and a metal tube affixed of such a 

 diameter as to slip over the eyepiece end of a micro- 

 scope ; this was fastened to the microscope tube by a 

 clamping screw. The box was blackened inside and 

 rendered light-tight, and answered quite satisfactorily 

 for low-power work. Although we do not advocate the 

 use of quite such simple apparatus as this, yet in place 

 of better, in the hands of a careful worker, it is capable 

 of giving good results. To illustrate this a photo- 

 micrograph of a diatom (Pleurosigma angulatum) taken 

 with this particular apparatus, using a T V inch objective, 

 and No. 41.c eyepiece is reproduced (Plate 41). Unless 

 care is used, the removal of the focussing sdreen and 

 insertion of the dark slide is apt to alter the focus, 

 especially if moderately high magnifications be attempted, 

 and it is better to have these simple cameras supported 

 on three or four legs, as shown at Fig. 10, particularly 

 as their weight is liable to cause the microscope tube to 

 slide down, unless a special clamp to prevent this is 

 supplied. The camera shown at Fig. 10, although in 

 essentials nothing more than one of these small cameras 

 supported on four legs, has several points of interest. 

 It is a simplified reflex camera of quarter-plate size. The 

 ground glass is at the side, a very convenient position 

 when the camera stands on a table, and the image is 

 projected on to it by a mirror which turns aside before 

 the exposure is made by means of a flap-shutter controlled 

 by a release. 



The Workroom. A workroom set apart for Photo- 

 micrography is not often available, but whenever possible 

 a table, shelf, or cupboard should be reserved for the 

 apparatus, which can then always be kept ready for use. 

 The dark room is invariably somewhat damp, and con- 

 sequently it is not advisable, even when space permits, 

 to keep the apparatus there. The best arrangement 



