( 495 j 
Bacteriology. — “On Indigo-fermentation”. By Prof. M. W. 
BEIJERINCK !). 
At a former occasion it was demonstrated *) that the indigo-plants 
may be brought to two physiologically different groups, viz. indoxyl- 
plants, to which the woad (satis tinctoria) belongs and indican- 
plants. Of the latter, which seem the most numerously represented, 
were examined Indigofera leptostachya, Polygonum tinctorium and 
Phajus grandiflorus*). The result was that they contain specific 
enzymes differing from one another, which split the indican into 
indoxyl and glucose, while in woad there is no such enzyme. 
Indican can moreover be decomposed by katabolism*), i.e. by the 
direct action of the living protoplasm, which has been observed in 
some indicanplants, beside enzyme-action. Various microbes, too, can 
decompose indican and here the decomposition is generally effected 
by katabolism only; some species, however, contain specific indigo- 
enzymes. Hence the word ‘indigo-fermentation” means two quite 
different processes: a katabolic and an enzymatic process, and the 
enzymes are of twofold origin, products of higher plants and pro- 
ducts of microbes. It is clear that in the formation of indigo from 
woad, in which no glucoside but free indoxyl occurs, there can be 
no question of „indigo-fermentation”’. 
1. Preparation of the Indican as used for the Experiments 5). 
For the preparation of indican-solutions from indican-plants, a 
method was described (l.c. p. 122) the principle of which is so 
quickly to destroy the enzyme that the glucoside can be dissolved 
without decomposition ®). This is best done for Indigofera and Po- 
lygonum by immersion in boiling water, by which an extract is 
obtained of 0.5 to 1 pCt. indican, which as such, or after mixing 
') IT am indebted to Mr. J. F. B. van Hassett and Mr. A. van DELDEN for as- 
sistance in the following study. 
2) “On Indigo-formation from the Woad (Zsatis tinctoria)”. Proc. Royal Acad. of 
Sciences, Amsterdam, Sept. 30, 1899, p. 120. 
*) Received under this name from a horticultural institution. 
*) For this expression see: Centralbl. f. Bacteriologie 2e Abt. Bd. 6. p. 5, 1900. 
5) Further informations about the indican and the enzyme of Indigofera are found 
in the recently published interesting paper of Mr. J J. HAZEWINKEL, Maandelijksch 
Bulletin van het Proefstation voor Indigo, Klaten (Java). Aflevering I, Januari 1900, 
Samarang. 
9) For the production of many other glucosides the same method can be applied, 
