MorGAN: POLARITY AND REGENERATION IN PLANTS 229 
This last experiment, while not satisfactory in all respects, yet 
suffices to show that the development of the basal buds in the 
long pieces is not due to the polarity localizing, as it were, the 
development at the base, nor to the flow of substances downward, 
but is due to the stronger buds being present in the basal region. 
These results recall the cases of Lilium candidum and Lachen- 
alia luteola, These plants do not set seed, but produce bulblets at 
the base. This formation of basal bulblets is attributed by Goebel 
to the flow of food substances in the plants towards the base which 
causes the bulblets to develop in this region, and at the same time 
deprives the seeds of the necessary material for their development. 
The explanation appears to me to be exactly the reverse. The 
buds that give rise to the bulblets in these plants are so vigorous 
that they utilize all of the food substances that are present, and 
thus deprive the seeds of food material that they might possibly 
make use of if the bulbs did not develop. It is not, I think, the 
flow of food substances downwards that causes the bulblets at 
the base to develop, but the vigorous bulblets in this region draw 
into themselves so much of the available food substances that not 
enough is left for the seeds. 
It might be claimed in the case of the burdock, that when the 
stalk, deprived of its leaves, is left attached to the old roots, mate- 
rial from the roots rising up into the stem will affect the basal 
buds first ; or it might be claimed that since there are large fibro- 
vascular bundles that go to the basal nodes these bring to this 
region materials from the roots that cause the buds to develop, 
but that this is not the real explanation was shown above by the 
experiment of removing the stem from the roots. The result ap- 
Pears to be due rather to the more vigorous condition of the basal 
buds. Whether, as I have said, this condition of the plant is itself 
to be thought of as ultimately the outcome of its polarity, is a 
question that I do not think we can profitably discuss as yet. £ 
it is, then the polarity in the growing point has already acted and 
determined the relative development of the buds in the different 
regions. When the piece containing these buds is removed, their 
further development is first determined by the stage that they are 
already in, or by their greater vigor, which may, in most vais 
mean the same thing. In the second place certain buds having 
gotten a start use up all or most of the available food materials 
and thus check the further development of the other buds. 
