98 MORPHOLOGICAL DEVELOPMENT. 



lower type. The gemmation by which these segments are pro- 

 duced, is as similar as the conditions allow, to the gemmation 

 by which compound animals in general are produced. As 

 among plants and as among demonstrably-compound animals, 

 we see that the only thing required for the formation of a per- 

 manent chain of gemmiparously-produced individuals, is that 

 by remaining associated, such individuals will have advantages 

 greater than are to be gained by separation. Further, by 

 comparison of the annuloid and lower annulose forms, we 

 discover a number of those transitional phases of integration 

 which the hypothesis leads us to expect. And, lastly, the 

 differences among these united individuals or successive 

 segments, are not greater than the differences in their posi- 

 tions and functions explain — not greater than such differences 

 are known to produce among other united individuals : wit- 

 ness sundry compound Hydrozoa. 



Indirect evidence of much weight has still to be given. 

 Thus far we have considered only the less- developed Annu- 

 losa. The more integrated and more differentiated types of 

 the class remain. If in them we find a carrying further of 

 the processes by which the lower types are here supposed to 

 have been evolved, we shall have additional reason for be- 

 lieving them to have been so evolved. If we find that in 

 these superior orders the individualities of the united seg- 

 ments are much less pronounced than in the inferior, we 

 > c hall have grounds for suspecting that in the inferior the 

 individualities of the segments are less pronounced than in 

 these lost forms which initiated the annulose sub-kingdom. 



