268 
Kny . — On Correlation in the 
containing terrestrial plants in which the sub-aerial and the 
subterranean parts are developed in due proportion : and it 
is with reference to these latter that the following interesting 
questions suggest themselves : — 
1. Does there exist between the roots and the shoots of 
a seedling such a correlation that the removal of the roots 
inhibits the development of the shoots, and vice versa ? Or 
is it not rather the case that the removal of the one part 
induces a more vigorous development of the other on account 
of the larger quantity of plastic material now available ? 
Or does the growth of the one part stand in no relation 
whatever to that of the other, in the developing seedling ? 
2. What is the limit to which the development of the 
shoots of seedlings will proceed after continued removal of 
the roots, and the development of the roots after continued 
removal of the shoots ? 
3. Are the phenomena of this kind which can be observed 
on isolated parts of adult plants (cuttings, tubers, &c.) different 
from those which are manifested by seedlings ? 
A. Experiments with Seedlings. 
It is obvious that some seeds are more suitable than others 
for experiments of this kind : the seed must contain either 
abundant endosperm or fleshy cotyledons, so that the de- 
veloping seedlings may have an adequate supply of organic 
nourishment available. 
If the experiments are to be carried out with complete 
exactitude, the seedlings must be grown, not in water, but in 
air saturated with moisture ; otherwise the uninjured seedlings 
will not be comparable with those whose roots have been 
removed, for the root is above all things organized for the 
absorption of water in the liquid form. Unfortunately there 
are difficulties in the way of practically carrying out this 
condition. The seeds of some species, such as Helianthus 
annnus , grow but little when kept on dry glass plates over 
water in bell-jars, and their roots soon show symptoms of 
drying up, Zea Mays proved itself to be the most suitable 
