IN VEGETABLE BIOLOGW 219 



brown with the bichromate. As already mentioned, copper 

 sulphate throws down a lavender precipitate with tannic acid, 

 with catechu a grey. 



The various reagents will be treated of seriatim. 



Action of Potassium Bichromate. — (a) Stem of Rosa canina. 

 Xylem, hard bast and cuticle are turned pale brown : funda- 

 mental tissue (including the collenchyma), soft bast, and cambium 

 a rich brown. 



(b) Stem o£ Isoetes lacustris. Meristem walls turned brown : 

 the xylem walls of the vascular bundles are naturally brown in 

 the spirit-preserved material used, hence it is difficult to say 

 whether the bichromate has any effect, but apparently it has. 



(c) Stem of the Pig. Xylem brown (yellow if the section be 

 thin) : hard bast and collenchyma yellower ; rest of fundamental 

 tissue, soft bast, and cambium still paler yellow. 



(d) Stem of Arundo Phragmites. Walls giving proteid re- 

 actions are coloured a light brown. 



{e) Stem of the Maize. The same as Arundo Phragmites. 



Action of Ferric Chloride. — (a) Bosa canina. A blue colour 

 is immediately seen in the collenchyma walls, and may be traced, 

 but very faintly, in the soft bast and cambium. This soon 

 passes away, and now the above tissues resemble the xylem and 

 hard bast, all taking a pale but distinct greenish colour. 



(b) Isoetes lacustris. Meristem walls pale greenish ; ditto the 

 xylem walls apparently, though the naturally brown colour 



interferes with the reaction. 



(c) The Fig. All tissues greenish : colour best seen in 



xylem, hard bast, and collenchyma; latex green. 



(d) Arundo Phragmites. Exceedingly faint greenish reaction 

 in walls giving proteid reactions. 



(e) The Maize. Lignified walls turned a light green. 

 Action of JSTesslers Fluid.— {a) Bosa canina. Fundamental 



tissue, soft bast, and cambium brown : xylem and hard bast pale 

 yellow, with faint suggestion of greenish, and signs of faint 

 browning in some of the walls. 



(b) Isoetes lacustris. Meristem cells pale yellow. 



(c) The Fig. Xylem, collenchyma and rest of fundamental 

 tissue, soft and hard bast pale greenish-jellow : latex yellow. 

 After a time a very faint pinkish hue can be detected in the hard 

 bast, and the latex becomes browner. 



LIXN. JOUIiX. — BOTA>T, VOL. XXIX. U 



