238 TRANSACTIONS OF THE [s 



E8S. LXXVIII. 



50 per cent, glycerine. The fuchsin occupying the lumina 

 is thus washed out, and with careful manipulation only the 

 cell- walls are stained. 



Mounting of Sections. — After washing, the sections are 

 mounted on a slide in 50 per cent, glycerine, the coverglass 

 being sealed with an easily prepared mixture of equal 

 quantities of gum mastic and paraffin wax (see " The New 

 Phytologist," March 1911). This is a convenient substance 

 for sealing, being very simply applied by means of a 

 slightly heated bent nail mounted in cork. The sections 

 will keep for any length of time, but should there be any 

 conceivable reason for remounting a section the sealing 

 substance can be readily removed. 



These operations, apart from the sectioning, although 

 appearing somewhat elaborate, are quickly executed and 

 occupy in all only a few minutes Moreover, several 

 sections can be treated at the same time. 



Microscope. — The magnification desirable for photograph- 

 ing sections of broad-leaved timbers is not usually high. 

 One of from 25 to 120 diameters is generally ample. It is 

 not necessary to possess an elaborate microscope with 

 apochromatic lenses, the ordinary, upright, student's micro- 

 scope with modern achromatic lenses being all that is 

 required for ordinary work. 



Illuminant. — Ordinary coal gas is the most convenient 

 for most workers, and this is quite a satisfactory source 

 of light. A suitable, incandescent, table lamp should be 

 purchased and connected by means of rubber tubing with a 

 gas bracket in the wall or on the bench (Flatters & Garnett 

 manufacture a very convenient inverted lamp with remov- 

 able chimney). A bull's-eye (2f-inch lens) mounted in a 

 ball-and-socket stand should be placed near the lamp, and 

 between it and the microscope, so as to throw the light on 

 to the concave side of the mirror of the latter. The 

 position of the bull's-eye should be so adjusted as to throw 

 the best light on to the mirror, the chimney of the lamp if 

 necessary being removed. 



Camera and Accessories. — The writer uses a Browning 

 " Microkam " (lantern size), which he has modified as 

 described below. As the modification adds vastly to the 

 utility of the camera, it is quite worth the few shillings 



