He would explain the serial homologies of such creatures as the lobster and centipede thus: Animals of a very low grade propagate themselves by spontaneous fission.

If certain creatures found benefit from this process of division remaining incomplete, such creatures (on the theory of "Natural Selection") would transmit their selected tendency to such incomplete division to their posterity.

In this way, it is conceivable, that animals might arise in the form of long chains of similar segments, each of which chains would consist of a number of imperfectly separated individuals, and be equivalent to a series of separate individuals belonging to kinds in which the fission was complete.
In other words, Mr.Spencer would explain it as the coalescence of {164} organisms of a lower degree of aggregation in one longitudinal series, through survival of the fittest aggregations.

This may be so.

It is certainly an ingenious speculation, but facts have not yet been brought forward which demonstrate it.