616 The American Naturalist. [July, 
their own use and that of the root. The roots also increased 
in circumference in proportion to the amount of their nourish- 
ment. This growth was excentric and preponderatingly under 
the cion. The following year blossoms were produced in the 
ordinary manner and death followed. Conclusion: If these 
shoots had remained on the parent plant, they would have 
blossomed the same season and died in the fall. Inserting 
them on the young root changed them into a vegetative state 
and prolonged their life for a whole year. In this case the 
young root exerted the controlling influence. In another ex- 
periment plants at the commencement of the second year were 
divided into two lots. The plants of one set were forced into 
a rapid development of blossoms; the others were restrained 
from blossoming by being kept in a cool place. The tops of 
the retarded plants were cut away and cions from the forced 
plants were inserted. The result of this experiment was quite 
different. These cions developed blossoms in the normal way. 
None of them remained short or formed the tufts of broad 
leaves which were peculiar to the sprouts in the previous ex- 
periment. In this case the leaves had long petioles and rather 
narrow blades as in ordinary blossom shoots. Here likewise 
the roots increased in size near the inserts, i. e. around them 
and below. Conclusion : Grafting on young and old roots leads 
to very different results. 
Knight’s law, expressed still more clearly by van Mons, 
that only its own nature controls the development of the cion, 
is not universally true. Cion and stock mutually influence 
each other always. Sometimes one preponderates in in- 
fluence, sometimes the other. The control exercised by the 
stock in these experiments with the beets is ascribed to move- 
ment of assimilative matters (stoffwechsel). The young root 
grows and stores up reserve materials, chiefly sugar. The old 
root does not grow, gives up its reserve materials, and dies 
after it is emptied. “It is plain,” says the author, “that the 
manner of growth of the bud, i. e. its development into a 
vegetative or floral shoot, depends less upon itself than upon — 
the parts bearing reserve substances, especially the roots.” 
