IS VEGETABLE BIOLOGY. 247 



reactions, proteid and non-proteid, he yielded by some non-proteid 

 substance stored up in special cells of the same plant, and yielded 

 in so definite a manner that precisely the same shade of colour, 

 peculiar to a certain type, is imparted by a reagent, proteid or 

 non-proteid, alike to cell-wall and to the substance stored up in 

 the special cells — if such a substance there be, then it is submitted 

 that the theories of Wiesner and of Fischer must stand aside 

 until its full examination has been carried out, and stand 

 aside with the odds against their reappearance as being, on the 

 supposition that the above-made statement can be substantiated, 

 quite unnecessary attempts to explain the phenomena in question. 



My attention was directed to glucosides, which we already 

 know to exist in the cell-wall. The method was first to try 

 whether one of these will give proteid reactions, and the follow- 

 ing were the results of this trial with the tannins. 



Here aud elsewhere (M), (X), (R), and (C) represent 

 Millon's, the Xanthoproteic, Easpail's, and the Copper Sulphate 

 and Caustic Potash reactions respectively. 



Effect of Proteid Reactions on Tannic Acid. — (M). A yellow- 

 ochre precipitate, becoming on boiling a warm brown with very 

 slight suggestion of madder. 



(X). Addition of hydric nitrate turns a solution of tannic 

 acid yellow : this deepens on boiling, and with ammonia becomes 

 a dark orange-brown, and quite black if the solution be strong. 



(R). When hydric sulphate is poured into a syrupy solution 

 of tannic acid it falls to the bottom of the test-tube, at the same 

 time producing a white precipitate in the solution: after some 

 hours the acid turns black and the precipitate pale pinkish. 



(C). A solution of Copper Sulphate gives a lavender pre- 

 cipitate, which Caustic Potash turns grey, and greenish on 

 boiling. 



This is not very promising. We see that (M) fails, as does 

 (C). (X) succeeds, and so does (R) to a certain extent. 



Effect of Proteid Reactions on a Solution of Catechu. — When, 

 however, a solution of Catechu is tried, the result is very different : 

 thus : 



(M). Grives a yellow precipitate, becoming dark brick-red on 

 boiling. 



(X). Hydric Nitrate gives a yellow colour to the solution, 



1 * « m _ _ — _ _ 



(R). The Hydric Sulphat 



ift 



