THE MORPHOLOGICAL COMPOSITION OF ANIMALS. 97 



surfaces a bud on each side. And M. L. Vaillant, after 

 citing this observation of M. Pagenstecher, gives an account 

 of a species of Syllis in which a great number of buds were 

 borne by a single segment. That the longitudinally- produced 

 gemmae which compose an Annelid, should thus have, one of 

 them or several of them, the power of laterally budding-off 

 gemmae, from which no doubt other annelids arise, gives fur- 

 ther support to the hypothesis that, primordially, the seg- 

 ments were independent individuals. And it suggests this be- 

 lief the more strongly because, in certain types of Ccelenterata, 

 we see that longitudinal and lateral gemmati m do occur to- 

 gether, where the longitudinally- united gemmae are demon- 

 si rably independent individuals. 



207. It would add to the probability of this conclusion 

 could we identify the type out of which the annulose type 

 may have arisen by the process of integration. I believe 

 there may be pointed out such a type a type which, by a 

 slight modification carrying somewhat further an habitual 

 mode of development, would produce not only a unit of com- 

 position for the annulose type, but also as a bond uniting it 

 with the other types, and these with one another. It is un- 

 desirable, however, here to enter upon the numerous explan- 

 ations involved by opening the question of these relation- 

 ships ; both because it would necessitate a long digression, 

 encumbering too much the general argument, and because, 

 being highly speculative, it would be impolitic to let the 

 general argument be even apparently implicated by it. 



But even supposing it impossible now to identify the unit of 

 composition of the annulose type, the foregoing evidence still 

 goes far towards showing that an annulose animal is an aggro- 

 gate of the third order. This repetition of segments, some- 

 times numbering several hundreds, like one another in all 

 their organs even down to those of reproduction, while it is 

 otherwise unaccountable, is fully accounted for if these seg- 

 ments are homologous with the separate individuals of some 



