204 GOEBEL: REGENERATION IN PLANTS 
Among higher plants Begonia isa goodexample. When parts 
of leaves are taken from plants of Begonia Rex in a flowering con- 
dition, these proceed to the formation of flowers much more 
quickly than those parts taken from plants not in flower (Sachs), 
and in Begonia discolor, which forms bulbils in the autumn, we get 
leafy shoots as regenerated organs in the spring, but bulbils in the 
autumn (Wakker). 
I have cited other examples of this relationship, which forms 
an important part of the theory of metamorphosis, in another 
place. 
4. The character of the organs formed in regeneration is de- 
pendent to a very slight degree only on outside factors. It is con- 
ditioned by the structure of the parts of the plants concerned, 
particularly by the direction in which the constructive material 
moves ; the wound-stimulus must also be taken into consideration. 
Véchting’s well-known investigations have directed the atten- 
tion of botanists to the polarity apparent in regeneration. New 
shoots are produced at the tips of old shoots, and roots from the 
bases. This process is reversed in root-cuttings. Leaves show 
“no polarity in regeneration ; the new organs appear at the base. 
The cause of these differences is the next point to determine. 
Vochting held that above all difference in growth was the deter- 
mining factor. Organs which have limited growth show regener- 
ation at the base; those which have unlimited growth show 
polarity. 
I can not agree with this conclusion. The relations described 
above are the ones which, in my belief, are to be considered most 
important. Ina foliage leaf the constructive materials are in the 
process of movement toward the stem. When we cut off the 
leaf, the new organs are in accord with the above idea produced 
at the base. In shoots and roots we have a double movement: on 
the one hand toward the vegetative point of the shoot, and on the 
other toward the vegetative point of the root. This implies the 
existence of polarity in these instances. 
Space does not admit the citation of all of the facts bearing 
upon this point, but a few examples may be mentioned. If Voch- 
ting’s theory were correct, a// organs of limited growth would 
necessarily show similar relations. But this is not the case. The 
