( 500 ) 
roots contain no enzyme}), as thin slices killed in alcohol, remain 
quite colourless in indican-solution at 45°. The same is the case 
with 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 to 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 of the indican agrees 
with that of the indoxyl in the fact that they are both completely 
wanting within the thicker stems 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 out 
the inflorescence which is then in the very period of the most intens- 
ive cell-partition and cell-elongation. Likewise, there is no indoxyl 
in the cambium and the secondary tissues of the woad-roots. Even 
the flower-buds are in an early period, and when still growing 
vigorously, free from indoxyl; likewise the embryos, 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 possibility 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 ammoniac-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 observable 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 
') While in the stem these parts are extremely rich as well in indican as enzyme. 
*) Which shows that the formation and accumulation of indoxyl is possible in the 
dark as well as in the light, 
