252 MR. S. LE M. MOORE's STUDIES 



* 



With Gnezda's fluid a yellow diffusible substance makes its 

 appearance : in fact the ammonia appears to act alone, just as 

 does the caustic potash of Nessler's fluid. Coagulated proteids 

 turn yellow with Gnezda's fluid, but it goes without saying that 

 this diffusible substance cannot be coagulated proteid. 



Proteid Reactions of the Tannin of Posa canina. — The funda- 

 mental tissue of the young stem was chiefly consulted, the 

 epiderm not being detachable ; the latter tissue was also experi- 

 mented with to some extent. 



(M). A dark colour — seemingly quite black — in cells with 



much tannin : this is pink-brown in presence of tannin in 



smaller quantity. 



(X). A good reaction, but the acid should not be boiled, only 

 warmed. 



(R). A beautiful brown-pink, like the colour taken by prim- 

 rose tannin. 



Copper sulphate gives a blue colour, and on boiling with 

 caustic potash a grey precipitate is thrown down. 



Gnezda's fluid throws down a pink-brown precipitate, be- 

 coming a little browner on addition of caustic potash. 



Proteid Peactions of the Cell-walls. 



It will here be advisable to present, in some cases iu more 

 detail than before, a statement as to the proteid reactions yielded 

 by the cell-walls of the types studied. 



(a) (M). Posa canina. Besides the good reaction in the xylem 

 and hard bast, there is a reddish yellow in the collenchyma, and 

 to a less degree in the rest of the extra-xylemic tissues. 



Isoetes lacustris, Fig, Arundo Phragmites, and Maize. As 

 already mentioned, with reference to the Fig, it is important to 

 remember that the reaction is given by the xylem, but not by the 

 hard bast or other tissues l}ing outside the xylem. 



(£) (X). Posa canina. Good reaction in xylem, hard ba*t, 

 and cuticle : faint reaction elsewhere. 



Isocles. Good reaction in xylem of vascular bundles of stem : 



pale reaction in the meristem. 



Fig. Besides the reaction of the xylem, a faint one is given 

 by the hard bast, and in the soft bast and cambium scarcely 

 any colour can be detected. 



Arundo and Maize as already mentioned. 



