244 Colonial Organisms. [March, 
reduction of the members of the colony to the condition of or 
gans of an individual, may be briefly concluded and perhaps 
strengthened by a reference to the sub-kingdoms of animal 
whose members appear to develop as individuals and not through 
colonization, and whose organs arise from special modification of 
the tissues of the individual body, and not from subordination of 
the separate members of a colony. There are three of thes 
sub-kingdoms, the Echinodermata, the Mollusca and the Verte 
brata. Of these, indeed, the first is supposed by Haeckel to ani 
from a colony, since he ascribes the star-fish to the original junc- 
tion of five worm-like animals. The evidence in favor of this, 
however, is-not convincing, and is not sustained by any distinct 
evidence of budding in the development of the embryo. lae 
gard to the Mollusca their individual derivation is unguestiot 
able, and their organs present no indication of assuming the typ 
cal molluscan form. The segmental character of a part of the 
body of the Vertebrata. has been adduced as an argument 
favor of their colonial derivation, but this argument is unsus- 
tained by any other evidence. There is no indication of segner: 
tation in the organs, none of which are successively ated, a 
in the Arthropoda and Hydrozoa. These organs indeed present 
every indication of originating in the transformation of the. 
sues of an individual, and display no evidence whatever ae 
dency to assume the parental form. The only indication e 
nial aggregation is in the segmental repetition of the v ai 
bones and their accompanying nerve ganglia, but this sega | 
tion may perhaps be better explained in another manner 
_In vertebrate embryology there is no clear evidence f “E 
mentation; and the lowest vertebrate, the lancelet, ane , 
vertebral characteristics very imperfectly. The Tunicata 
some indication of a connection with the Vertebrata by e this 
mentation of their posterior body in the embryo state, | wnt 
very low stage in the. line of, vertebrate development 15 jo the 
unlike the accordant. stage of articulate development pe 
latter each segment is furnished with nearly all the organ? de 
sy fon individual life. - In the former the functional. Pe 
velop within the anterior undivided body, and the ‘ 
is limited to the tissues of the tail, and is perhaps due t° Firan 
of: flexibility in the Swimming motion of a homogeneous i. 
1 See Led Evolution of Organic Form,” Pop. Science Monthly, Novas 1880 £ A 
