1913-14.] BOTANICAL SOCIETY OF EDINBURGH 239 



spent on it. The " Microkam " as sold consists of a well- 

 made, rigid, wooden box, fitted with a hinged dark shutter, 

 and grooved at one end to take the dark slide and focus- 

 sing screen provided. At the other end is a projecting 

 nozzle intended to fit into the microscope tube, but such an 

 arrangement necessitates the removal of the eyepiece, and 

 this greatly reduces the magnification. It is to overcome 

 this drawback that the following modification is desirable 

 (see fig. 1). A short length of thick brass tubing, the 

 outside diameter of which is slightly greater than the 

 milled head of the eyepiece, is fitted to form a collar round 

 the upper end of the microscope tube. The nozzle of the 

 camera must be removed and replaced b} T another whose 

 internal diameter exactly corresponds to the external 

 diameter of the brass collar fixed to the microscope. By 

 this means the camera can be attached to the microscope 

 without the removal of the eyepiece. This is a great 

 advantage, for the use of the eyepiece obviously ensures a 

 much higher magnification, and compensates for the absence 

 of an extension bellows, while the modification in the 

 camera does not preclude the possibility of working, if 

 desirable, without the eyepiece. It is an advantage to use 

 a screen of ground glass to secure even illumination. A 

 piece the size of a lantern plate answers admirably. It 

 can be fixed underneath the stage by means of an india- 

 rubber band if there be no substage condenser in the way. 

 If the ground glass cannot be so fixed, the screen can be 

 placed with the ground surface downwards on the stage 

 itself. There is little danger of the uneven surface of the 

 glass coming into focus with the section. It is always a 

 safe, and indeed where no eyepiece is used a necessary, 

 procedure to dull the inner surface of the microscope tube 

 by inserting a lining of velvet. To ensure the rigidity of 

 the lining, the velvet is mounted on stiff but flexible paper 

 and rolled into a tube which just fits the microscope tube. 

 The paper, tending, as it does, to unroll, keeps the lining, 

 which, unmounted, would obtrude itself into the field of 

 view, closeky applied to the inner surface of the microscope 

 tube. As the camera is firmly attached to the microscope 

 the effect of vibrations is minimised, since the camera 

 and microscope vibrate together. The plates the writer 



TRANS. BOT. SOC. EDIN. VOL. XXVI. 18 



