340 



and Pliajus agrcc in so far as in both indigo-fermentation is causeil by katabolism 

 and by enzymes; but they differ in the fact that in Pliajtts the katabolism is quickened 

 by high, in Polygonuin by tozu temperattire. In Indigofera katabolism seems not to 

 occiir at all and the decomposition of indican appears exclusively effected by the 

 enzyme. 



From the preparations obtained in the way described, the enzyme itself can but 

 be imperfectly extracted. In water it proves almost quite insoluble, somewhat better, 

 in glycerine and best of all in a lopCt. solution of common salt, as was already indi- 

 cated by Mr. Hazewinkel, and in a lopCt. solution of calcium chloride. In these so- 

 lutions only a small quantity of enzyme is soluble, for the remaining substance is 

 nearly as strongly active as before the extraction. In the solutions themselves alcohol 

 produces hardly any precipitate, so that more active preparations cannot be procured 

 in this way. Accordingly the best results in the enzyme experiments are obtained by 

 crude enzyme finely powdered. 



j. On the Distribution of Indican and the Indigoemymes in the Plants. 



By the examination of the difïerent parts of indigo- and other plants in the two 

 ways described, the distribution of the indican and the indigo-enzymes was esta- 

 blished. It was thus made evident that both commonly occur or lack together. 



They are accumulated in the leafy organs, especially in the green leaves; in flo- 

 wers and flower-buds they are in smaller quantity. In the seeds and germs they fail 

 entirely. The roots and stems of Polygonum tinctoritim and of Indigofera lepto- 

 stachya are also quite or nearly quite devoid of indican and indigo-enzyme. Only in 

 transverse sections of branches of the latter, kept for some days in strongly diluted 

 indican solution, I could detect traces of indigo-blue particularly in the medulla aml 

 the medullary rays and in the bark, which shows that these parts contain some, btit 

 very little-indigo-enzyme. The absence of enzyme and indican in the stem and roots 

 of Polygonum tinctoritim can be easily shown as the stems of this plant have a great 

 disposition to form radiculae which are, as the stems, by their herbaceous nature and 

 broad-celled structure, quite fit for such experiments. If the roots are allowed to die 

 off in a chloroform-atmosphere they remain colourless ; this is likewise the case when 

 the dying is occasioned by iminersion in mercury foliowed by treatment with am- 

 moniac vapour. But from this follows only that indican and enzyme do not occur 

 together; if but either of them is present it is not detected by this experiment '), but 

 may be demonstrated as follows. 



If indigo-enzyme is added to a decoction made from the stems or roots of Poly- 

 gonum tinctoritim, or if this decoction is boiled with hydrochloric acid and a little 

 ferrichlorid to decompose the indican and oxidise the indoxyl, then no indigo appears; 

 so, indican is absent. 



That in the said parts indigo-enzyme, too, is wanting follows from the fact that 

 parts of stems and roots finely crushed in alcohol, after filtering, off and drying, pro- 



') This shiiuld be kcpt in view with ri'^ard tn the »aIcohol-e.xpcriim-nt« <>f Mr. 

 M ol i SC h. 



