248 Colonial Organisms. [March, 
the most highly evolved members of the plant colony. The plat 
stem which connects these individuals resembles the stem of the 
Coelenterate colony in its vascular function, But the plant colony 
has the peculiar feature that it includes two distinct forms o 
nutritive individuals, each absorbing a special kind of nutriment 
The water and the nitrogenous elements of the food are ab 
sorbed by the roots, the carbonaceous by the leaves. Just wher 
the chemical combination of these various elements into prott 
plasm takes place, whether in the leaves or the stem, is not knows 
It appears, from these considerations, that the tree is net 
colony ina simple sense, as in the Polyzoa, in which precise | 
similar individuals are aggregated; but in a complex sense, asti 
the Hydrozoa, in which each individual performs but a part d 
the life functions, and is dependent upon other individuals for th 
remainder. Thus the tree is, in one sense, an individual, wi 
three kinds of organs, but in a truer sense, a colony of pat) 
subordinated individuals. oe 
The third form of organ, or member of the colony, the re" 
ductive, is in its origin a modified leaf group. It has no nu 
powers, its sole duty being sexual reproduction. This rept? aA 
tive function we need to consider in conclusion. The plant T 
ony, like the animal colony, is built up by asexual sa j} 
These buds, in the higher plants, attain a considerable deg | 
-development ere their individual life begins. They enter 1 
their life duties neither as simple cells nor as simple leaf "o 
but as leaf colonies. Thus the product of a rane | 
t loses t” E 
h its 10 
nce of “Ae 
acts as a compound individual. This is another insta | 
celeration of Development,” an advanced degree of deví throw FE 
being attained under the parental care, ere the offspring a 
upon its own resources as an active individual. pe ot | ) 
In régard to the sexual individuals a still more declar 5 18 i 
eration is evident. In this respect the history of ph prodit. 1 
parallel with that of animals. In the lowest forms eT q 
of sexual “conjugation” is a single cell, which is at mt l 
‘upon its own resources for development. In somew ich ; l 
forms, as in the higher Fungi, asexual germs, pê woe 
‘Protoplasm, are’shed as free individuals, and grow itO 
