250 MR. S. LE M. MOOBE'S STUDIES 



(d) Arundo Phragmites. "Walls giving proteid reactions are 

 turned yellowish green. 



(e) The Maize. "Walls giving proteid reactions take a yel- 

 lowish-green colour. 



Action of Copper Sulphate. — (a) Rosa caninct. Collenchyma, 

 and to a slighter extent rest of cortex, soft bast and cambium 

 turned a lavender colour : xylern and hard bast a faint yellow. 



(b) Isoetes lacustris. Meristem walls no appreciable effect. 



(c) The Fig. "Walls of hard bast take a lavender hue ; this 

 is seen but faintly in the other extraxylemic tissues, best in the 

 collenchyma. Xylem as xylem of Rose. 



■ 



(d) Arundo Rhragmites. "Walls giving proteid reactions turn 

 faint greenish yellow. 



0) The Maize. Ditto. 



To these reiiifts may now be added some macroscopic ones 

 yielded by tissues which give more or less clear proteid reactions. 

 Take three pieces of bottle cork, moisten thoroughly a face of one 

 piece with ferric chloride, of the second with JN"essler's fluid, 

 and of the other with potassium bichromate: after a little time 

 the first will be green, the second brown, the third yellow-brown. 

 These observations upon cuticularized tissues are given here, but 

 no attempt has been made in this research to study such tissues 

 fully. The greening of cork with ferric chloride must be familiar 

 to anyone who has taken u steel-drops " kept in a corked bottle. 



Dip the end of a match into ferric chloride — it will dry 

 green : another match-end dipped in Nessler's fluid will dry 

 yellow, a third dipped in potassium bichromate brown. 



[It may be mentioned that a match-end gives a good (M) 

 reaction and a fair (X) one. "With pieces of cork (X) succeeds 

 admirably, if the precaution be taken of thoroughly softening 

 them with hydrochloric acid before boiling; (M) also gives a 

 reaction, but not a good one, apparently from the difficulty of 

 wetting the cork thoroughly.] 



Some Reactions given by Tannin in the Riant. 



"We will now go a step further and inquire how tannin behaves 

 in the idioblasts and ordinary cells of certain plants. In this 

 part of the research it is well to remember bow clear an answer 

 to questions about tannin is frequently given by tissues at or 

 near the surface. There are several reasons, I take it, why 

 tannin should be found here, for 



