341 



duce a powder quite inactive on indican-solution. Even the jjrowing point and the 

 region of growth of the roots contain no enzyme »), as thin slices killed in alcohol, 

 remain quite colourless in indican-solution at 45". The same is the case witli entire 

 roots which, after killing in alcohol, are put in indican-solution. 



From these facts seems to follow that the growth and development of indican- 

 plants is not in inseparable relation te the presence of indican and enzyme. 



To this result we are also led concerning the relation between the development 

 and the presence of indoxyl in the woad, though its distribution in this plant is 

 somewhat different from that of the indican. In woad the indoxyl occurs, besides in 

 the young leaves, and buds, also in the young rootperidermis, in the root-buds and in 

 the growing root-ends =). The distribution af the indican agrees with that of the 

 indoxyl in the fact they are both completely wanting within the thicker sterns and all 

 the thicker roots. So there is in woad no indoxyl in the inner part of the stem organs 

 of the leaf-rosettes in spring, when they are ready to elongate and push nut the in- 

 florescence which is then in the very period of the most intensive cell-partition and 

 cell-elongation. Likewise, there is no indoxyl in the cambium and the secondary 

 tissues of the vvoad-roots. Even the flower-buds are in an earlv, period, and when 

 still growing vigorously, free from indoxyl; likewise the enibryos, seeds and fruits. 

 First at the germination indoxyl can be pointed out in the seeds and other parts of 

 the germinating plant. So it is very probable that neither indican nor indoxyl are 

 necessarily related to the growth or development of the indigo-plants. But the possi- 

 bility remains that in certain cases these substances originate as quickly as they dis- 

 appear. So, in the young leaves of Indigofera leptostachya, when kept some days in 

 the dark, a little indoxyl may be detected by means of the ammnniac-experiment, while 

 the normal plant is in all its parts quite free from indoxyl, whence it seems possible, 

 that in normal conditions, there is a continual splitting of indican, which is not ob- 

 servable only because the freed indoxyl directly forms indican again with freshly 

 supplied sugar. For the rest, the woad, of which all full-grown parts are devoid of 

 indoxyl, proves that this substance can relatively quickly disappear. 



The appearance of indican, particularly in the peripheric parts of the aerial 

 organs, and the bitter taste it gives them, might suggest the idea that, like tannin, it 

 serves as a defensive against insects and snails. But this supposition would explain 

 only the function of the indican but not that of the splitting products and the indigo- 

 enzyme. If a beneficient influence on the growth in general could be ascribed to in- 

 doxyl, then a useful action of this substance on the curing of hurt parts would become 

 probable. And this would also spread more light on the function of the indican and 

 the enzyme, for then it would be clear that the enzyme-action. which operates at the 

 very dying oft' of the hurt cells, would promote the curing, not only by tlie formation 

 of indoxyl but also by the production of glucose. 



As to the localisation in the cell, I found the leaves of Phajus grandiflorus by 

 their broad-celled structure fit for demonstrating microchemically indican as wcll as 

 indigo-enzyme. 



') While in the stem these parts are cxtrcniely rich as wcll in indican as enzyme. 

 -) Which shows that the f()rmati<in and accunuilation ut indoxyl is possible in the 

 dark as well as in the light. 



