656 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



(4) Photomicrography. 



Practical Photomicrography.*— Fig. 94 shows a simple and very 

 inexpensive apparatus which J. Jullien has found very satisfactory, and 

 which any deft amateur can adapt to his Microscope. The apparatus is 

 essentially composed of a rectangular wooden box of exterior dimensions 

 27 x 27 x 62 cm. One of the larger sides forms the door, accurately 

 closing by means of two pins. The bottom is pierced with a round hole 

 12 cm. in diameter, to which is fastened a sleeve of black stuff, supple 

 and light-tight. The Microscope tube fits into this sleeve and is secured 

 by a running string. The interior of the box is completely varnished in 



Fig. 94. 



dull black. Any ordinary strong double shutter can be used — with a 

 certain modification, however, viz. that the dividing partition is to be 

 done away with, and the ground glass put in exactly the place which the 

 sensitive plate will afterwards occupy. In this manner any difficulty as 

 to difference of focus between the surface of the matt-glass and the sensi- 

 tive plate will be avoided. The light-source (gas, incandescent lamp) is 

 set about 40 cm. from the Microscope mirror, and a monochromatic 

 filter is placed between the light-source and the mirror. 



As an economical method of making a monochromatic filter, the 

 author recommends an unexposed sensitive plate which should be first 

 fixed in hyposulphite and washed as a negative. It should afterwards 



* Bull. Soc. Zool. de Geneve, 1908, pp. 101-4 (1 fig.). 



