The Polar Organizatio. of Animals. 495 
point of view it becomes interesting to find that the outer layer, 
the sensory region of the body, is the normal seat of ingestion of 
oxygen. This is particularly the case in the lowest animals. 
Food is ingested and dealt with by the interior substance of the 
body. Energy and oxygen, the agent of energy, are absorbed 
| This polarity of the function of oxidation is 
sity of protection of the oxygen-absorbing tissue causes its inclu- 
sion within the body, though in the highest forms it retains indi- 
cations of an invagination of the ectodermal tissue, as in the gills 
of fishes, and the lungs of land animals with their special nasal 
channel of external communication. 
In one kingdom of the organic world, the vegetable kingdom, 
which the sensory function fails to develop itself, the oxygen- 
ating function takes its place and becomes’the anterior pole in a 
igitudinally polar organism. The symmetry of plants is, in 
a, closely analogous to that of animals. In all the higher 
toms of the plant world we find a cylindrical, elongated trunk 
branching extremities. The two sets of branches are funda- 
aan identical, though they differ through the influence of 
fä nal differences. A tree, however, is a colony, and we must 
i 
upon the product of a single bud, with its cylindrical stem, 
€s and rootlets, as the individual vegetable organism. 
7 here no sensory pole, but there are analytic and syn- 
poles, The leaves absorb oxygen, the rootlets absorb food. 
er answer to the lungs, the latter to the intestines of ani- 
But as these functions are here complicated with, and sub- 
aed to, no higher ones, they become the principal mold- 
agencies, and the plant becomes a symmetrically polar oxy- 
$ Organism. It probably possesses the double polarity 
Clearly exists in animals. The lateral, sexual polarity of 
“S seems to be replaced by a cylindrical polarity in plants, 
ier and outer layers of active tissues which bound the sap 
Perhaps Possessing these opposite polarities. The other 
a ae of oxygenation and nutrition, is a longitudinal one; 
e the higher plant, as distinctly as the higher animal, is 
ded by its internal constitution, and owes only its less 
“al, Specific differences to the influence of external 
ich 
zm not carry this consideration further. It certainly 
