164 TEAXSACTIONS AND PROCEEDINGS OF THE [Sess. lxiii. 



events, I was unable to get the developable image. Further 

 experiments are in progress with this method. 



The photo-chemical process gave, for the work in hand, 

 quite satisfactory results, and my method of using it is as 

 follows : — 



Preparation of the Sections. — The material from which 

 the sections were cut was in most cases typical blocks of 

 wood, which had been seasoned ten, fifteen, or more years 

 ago, and which had been used as museum specimens. 

 From these, hand-plane sections were prepared, as large 

 and as thin as possible. Xaturally, these sections were 

 extremely brittle, and betrayed a tendency to curl up, 

 which rendered manipulation difficult. The largest of 

 these, in some cases six inches long and two to three inches 

 broad, were immersed for twenty-four hours or more, 

 according to the character of tlie wood, in a flat dish 

 containing a mixture of absolute alcohol and glycerine, 

 about half and half, and kept flattened by a glass plate. 

 This treatment got rid of the air, flattened the sections, and 

 removed the brittleness to a workable extent. Thence they 

 were transferred to the staining fluid. In the choice of this 

 last, one had to be guided by various considerations, more 

 especially a stain had to be selected that would give good 

 contrasts and differentiation, not merely in the actual 

 section, but which would show as such on the developed 

 plate, A series of experiments made on these lines with 

 various stains, alcohol or water soluble, proved that, of 

 all, Bismarck Brown or Orange G. in saturated watery 

 solutions gave the best results. After prolonged staining, 

 the sections were toned with spirit, dehydrated with 

 absolute alcohol, and left in oil of cloves for a day or two 

 if intended ultimately for mounting in balsam. If to be 

 mounted in glycerine-jelly, the sections were transferred 

 from absolute alcohol to absolute and glycerine, half and 

 half, and then into pure glycerine. 



Printinff. — The sections thus cleared are used as 

 negatives, so to speak, for direct contact printing with 

 lantern plates. A plate of glass is fitted into the ordinary 

 printing frame, and on this the series of wood sections is 

 arranged, in a thin layer of oil of cloves, or of glycerine, as 

 the case may be. In the dark room an ordinary lantern- 



