52 LABORATORY NOTES, 
remembered that, except very rarely (e. g., Strychnos Ignatia), the 
ordinary methods employed to demonstrate continuity involve 
action of the reagent during several hours, the advantage of the 
plan here proposed is at once obvious. 
III. Action or coup Minton’s FLUID ON IRON-GREENING TANNIN, AND 
CELL-WALLS GIVING PROTEID REACTIONS. 
In a memoir recently published in Journ. Linn. Soc. vol. xxvii. 
I have endeavoured to show that the substance in certain cell-walls 
: y 
various reagents employed, whether those reagents be reagents 
me ev 
dered in favour of the view that the presence of tannin (or at least 
of some glucoeide) often determines the colour taken in these cases. 
As I 1ere writing about Millon’s reagent, the opportunity is 
taken of stating that, in the course of some farther researches on 
this interesting subject, an unsuspected confirmation of the above 
doctrine has lately come to light. I find th 
on’s fluid is added to a solution of tannin, no change in the 
yellow ochre-coloured precipitate * ensues on allowing the unboiled 
product to stand overnight, yet that with an iron-greening tannin in 
the form of a solution of catechu, the result is quite different, since 
the precipitate slowly becomes brick-red without boiling. Here then is 
till favours continental views can 
easily apply. If the substance in the cell-walls which react like 
the result of the experiments is here given: in each case 
Fatih were kept overnight in Millon’s fluid, but usually three or 
lent, 
a). Icy. Xylem, hard bast and to a less degree outer cortical 
ayers and epidermis aot as on boiling in the fluid. Th i 
a sclerotised f i i 
fnnér side of thé xelam undamental tissue lying upon the 
* If the solution be a stron ea : : 
soon becomes ochre-coloured, § one, the precipitate is at first orange, but it 
