1286 
can be converted into slime, that is a mutant capable to produce 
slime from carbohydrates only and not from proteids. 
A great number of other examples might be added demonstrating 
that the speculations about the heredity units or factors have relation 
to enzymes. 
7 
Limitation of the enzyme conception. 
In my opinion the preceding may lead to a better enzyme con- 
ception than the existing. I will try to elucidate this by a few in- 
stances taken from the cecidia or galls and the substances called 
ferments in immunology. 
Elsewhere I pointed out that the change of the plant at gall-for- 
mation is not hereditary. From the galls of Nematus viminalis, kept 
on moist sand, quite normal roots of the gall-bearer Salix purpurea, 
and from those of the gall-fly Neuroterus lenticularis on oak-leaves, 
quite normal oak roots may arise. ’*)- 
From the axil-buds of the willow-rose, caused by Cecidomya 
rosaria on Salix alba, 1 have cultivated quite normal willow trees; 
likewise I grew normal plants of Poa nemoralis from the bud in the 
remarkable gall of Cecidomya poae, whose strange metamorphic roots 
readily develop into normal roots, when the whole gall is planted 
in earth.*) By strongly pruning the twigs of Rosa canina whereon 
Bedeguars developed, caused by the gall-fly Rhodites rosae, the wonder- 
ful appendices of this gall changed into long-petiolated, simple, - 
green leaflets, whose anatomic structure and external appearance were 
quite identic with those of the leaf on which the gall originates. 
These instances, to which I could easily add others, show that in 
the formation of galls two groups of substances are concerned: the 
protoplasm of the plant, consisting of the unchanged heredity units, 
and substances deriving from the egg of the gall-animal, or from 
the larva of Cecidomyia, which evidently have the character of 
enzymesubstrates. It is however clear that the heredity units con- 
cerned in the morphologically higher galls, multiply more intensely, 
in any case become more numerous under the influence of the gall- 
animal than under normal circumstances. Hence we come to the — 
conclusion that either the enzyme-substrates may serve as food for 
the heredity units or enzymes to which they belong and may give 
rise to their multiplication, or that the gall-animal, beside the enzyme 
‘) Only very few Lenticularisgalls possess this disposition, which is probably 
connected with the spot where the gall grows on the leaf. 
*) Botanische Zeitung 1886. 
