OCCURRENCE OF CRYSTALS IN SOME AUSTRALIAN TIMBERS. 437 



obtained which made it possible to determine the crystal- 

 line system without any breaking down of the wood or any 

 preparation whatever, viz. plates or prisms of the mono- 

 clinic forms. 



They occur with few exceptions in a specialised form of 

 chambered wood parenchyma, with partitions dividing it 

 into cells- of about equal size containing as a rule an 

 individual crystal, but, in one case of ray parenchyma, as 

 many as four were found in a cell, viz : — Mallotus phillp- 

 pinensis, Natural Order Euphorbiaceae. 



The micro-sections of timber were prepared by long 

 immersion in strong hydrofluoric acid, which, however, 

 appears to have had no effect upon these crystals of calcium 

 oxalate, and this insolubility is no doubt further aided by 

 the protective property of the cell walls. 



In the case of Strychnos arborea, N.O. Loganiaceae, how- 

 ever, they were found in long pockets in great abundance, 

 giving the wood the appearance of having been marked with 

 chalk streaks on a longitudinal section, or as distinct white 

 spots on a cross section, as shown in Plates XXX, XXXI. 

 The hydrofluoric acid, however, appears to have had some 

 effect on this material, or at least the greater part was lost 

 in the slide preparation. It is possible, however, that the 

 diameter of these sacs or pockets being so large the sub- 

 stance fell away. Plate XXX shows this substance in situ 

 with numerous crystals amongst the matrix. I am indebted 

 to Mr. J. H. Maiden for this particular specimen of timber 

 upon which the research was made. 



It is common amongst artisans to speak of a particular 

 wood as " having a grit," two Australian woods being 

 notorious for this special physical property, viz : — Euca- 

 lyptus pilularis, " Blackbutt," and Tristania conferta, 

 " Brush Box." An examination of these showed them to 

 be more or less permeated in the vessels with silica rather 

 than with this substance. 



