EVIDENCE FROM COLONIAL OR COMPOUND ANIMALS. 305 



firstly, the original and primitive condition of all organic beings is a 

 colonial condition. This phase is exemplified, primarily, in the 

 segmentation of the egg and in the cell-multiplication of plant-germs ; 

 two features of so universal occurrence that we may lawfully claim 

 for them a great importance in the evolution of the organism and a 

 high antiquity in the history of living things. It is likewise imitated 

 in the so-called asexual reproduction of the lowest animals, repre- 

 sented by the gregarinse and amoebae. A second conclusion that 

 follows from the teachings of development may be expressed by say- 

 ing that this tendency to division of substance is most typically seen 

 in lower organisms, where, as exhibited in the sponges, zoophytes, and 

 their allies, the constitution of the individual is undeniably compound, 

 and where its advance is marked merely by the multiplication of 

 new types of colonial and connected units. We discover, thirdly, 

 that the tendency to degradation and retrogression may likewise 

 plainly develop the compound and colonial state. It is highly 

 probable that the tapeworms', the ordinary worms, and even Articulate 

 animals themselves, illustrate cases in which a primary development 

 of like segments or colonial units through arrest of growth, and 

 through simple bodily division and repetition of like parts, has paved 

 the way for succeeding modification of the colonial type. If the 

 evolution of the centipedes, insects, spiders, and crustaceans from a 

 lower worm type be accepted as proved, or even as probable, the 

 characteristic features of these animals must have been fundamentally 

 derived from those colonial tendencies we see exhibited in the worms 

 of to-day. A fourth conclusion teaches that the plant-world is 

 markedly colonial even in its highest types. The vegetative repeti- 

 tion of bud, leaf, and flower is simply a pure indication of colonial 

 constitution exhibited in all that perfection of detail which has 

 escaped the more forcible modification of the animal series. A 

 fifth inference directs attention to the essentially colonial consti- 

 tution of even the highest animals, as exhibited in their cellular 

 structure, and more especially in the independent constitution of 

 many of their component cell-elements. And a sixth and final 

 conclusion is deducible from our studies namely, that concentra- 

 tion of structure and function, and the metamorphosis of the colony into 

 the true individual, is at once a cause and a result of the progressive 

 tendency of life at large. The higher we rise in the scale of being, 

 the more united and specialised do structure and function become. 

 Such a tendency is represented, as we have seen, even amongst plants, 

 in which the colonial and compound type tends to resolve itself into 

 the simpler and more individualised phase. At the same time, we 

 must recognise that, despite the functional unity of the highest 

 animals, there remains in their relative cellular independence the 

 traces of a colonial constitution, once universal, and still linking 



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