148 Colonial Organisms. [February 
they seem to possess some degree of vascular and sensory Con- 
nection. 
A somewhat more progressed case is presented by the Actino- _ 
zoa, in which the colony is united by a common stem, which i$ 
fed by the united labors of the feeding individuals, and through 
which these individuals possess some degree of vascular, sensi 
tive and motor connection. The separate members of the colony 
' here take a first step towards reduction into the organs of a com- 
plex individual. | 
In the Hydrozoa this subordination is much more declared. 
Each member of the colony has lost a portion of its life powe 
and is thus an incomplete individual. Some feed only, and have 
ceased to reproduce. Others reproduce only, and have ceased t0 | 
feed. The colonial life is a necessity, since each individual hes | 
lost a portion of its life powers. From being individuals p% 
sessed of all the life functions, they have become organs gi 
composite individual, but organs which are as yet, in nearly ê 
complete sense, individual animals. If now we consider g 
swimming Hydrozoan colonies, the Siphonophora, a remarkable 
development of this principle of subordination makes its appear | 
ance. These complex animals yield strong indications of an of 
gin in colonies of individuals, which have become quite inapt = 
of a separate life. Each has lost not one only but several of 18 
organic powers, and is reduced to the performance of a siis 
duty, while dependent on its differently-developed neighbors a 
aid in its other duties. The original individuals have become 
graded into organs through this loss of ability and limitation 
their field of labor. Thus, at the extremity of the gener BS 
of the Siphonophora, there is usually an individual converted 
to a simple bladder, and useful only for purposes of ioe 
Beneath it are a number of others which act only as swim 
bells, their sole duty being to rythmically contract and exp 
On the remaining portion of the stem are individuals, en 
which act as food catchers, others as mouths and GIS" s 
organs, others are limited to reproductive activity, and 0 jf 
again are reduced to mere covering pieces, in which all the ó 
organs have disappeared, and which seem intended me 
protect the more active individuals. The common comm se 
stem acts as a vascular system, and probably possesses 
degree of sensory and motor activity. | 
