308 Leake . — The Localization of the Indigo-producing 
Dictionary of Economic Products ( 18 ). I can find no account of the 
localization of indigo in this plant, and on the present occasion opportunity 
has only offered for examining the stems and leaves of plants cultivated 
in Bengal. To the naked eye the deposition of indigo-blue produced by 
the sulphuric-acetic-persulphate reagent appears greater in the tissues of 
this plant than in those of any of the species previously considered. 
Microscopic examination, after sectioning and staining, indicates that 
the blue is deposited in practically all tissues. The xylem-vessels alone 
are free from indigo. Traces indeed occur even here, but it is probable 
that, in a moderately succulent plant like the present, the mere cutting 
of the fresh tissue across the vascular bundles will transfer from the injured 
mesophyll-cells to the xylem-vessels a certain amount of cell-sap which, 
though small, will be sufficient to cause a deposition of blue in the latter. 
With this exception indigo may be said to be deposited in abundance 
in all tissues. The large, elongated cystolith-cells are especially prominent 
(Fig. 14) owing to the dense mass of blue deposited in them and around 
the cystolith. In the leaf the epidermal cells, including the guard-cells 
and the two forms of epidermal hairs (Fig. 15), the mesophyll, the 
collenchyma of midrib and lateral veins, the parenchyma of the vascular 
bundles and the sieve-tubes all contain indigo. In the stem the cortical 
collenchyma and the thin-walled chlorophyll containing parenchyma (Fig. 
16), the xylem-parenchyma, the phloem-parenchyma, the few scattered 
fibres of the phloem and sieve-tubes and the pith similarly contain a 
deposit of indigo within the cell-plasm. The xylem-fibres, which form 
the greater bulk of the older stem, contain only traces, and the same may 
be said of the cambium (Fig. 17), which is npt, however, very prominent. 
Here again, therefore, indigo is only absent from the xylem-vessels. 
No opportunity has yet occurred of examining the flowering stem and 
organs of reproduction. 
The Supposed Relation between the Chloroplast and the 
Indigo-producing Substance of the Plant. 
Molisch, after an examination of Phajus grandifolius , Calanthe vera- 
trifolia , I satis tinctoria , and Indigofera sp. concludes (8) : — 
c Erstens, dass die Chlorophyllkorner der Indicanpflanzen, wenn auch 
nicht den ausschliesslichen, so doch den Hauptsitz des Indicans darstellen, 
und zweitens, dass hiermit die Anwesenheit eines stickstoffhaltigen 
Glykosids im Chlorophyllkorn der genannten Pflanzen zum ersten Male 
nachgewiesen erscheint.’ 
The method already described for precipitating indigo within the 
tissue is used for the examination. An examination of the figures given 
by him are not convincing ; moreover, Molisch himself shows that indigo 
