THE MORPHULOGTCAL COMPOSITION OF A^JIMALS. 



93 



consists of mitransformed cells. The first appreciable change 

 is an elongation and a simultaneous commencement of seg- 

 mentation. The segments multiply by a modified gemma- 

 tion, which takes place from the hinder end of the penultimate 

 segment. And considerable progress in marking -out these 

 divisions is made before the internal organization begins. 

 L'igs. 163, 164, 165, represent some of these early stages. In 



yes 



Annelids of other orders, the embryo assumes the segmented 

 form while still in the q^^. But it does this in just the 

 same manner as before. Indeed, the essential identity of the 

 two modes of development is sho^Ti by the fact that the seg- 

 mentation within the q^^ is only partially carried out : in 

 all these types the segments continue to increase in number 

 for some time after birth. IS^ow this process is as 



like that by which compound animals in general are formed, 

 as the different conditions of the case permit. When new 

 individuals are budded-out laterally, their unfolding is not 

 hindered — there is nothing to disguise either the process or 

 the product. But gemmae produced one from another in the 

 same straight line, and remaining connected, restrict one 

 another's developments ; and that the resulting segments are 

 so many gemmiparously-produced individuals, is necessarily 

 less obvious. 



I 206. Evidence remains which adds very greatly to the 

 weight of that already assigned. Thus far we have studied 

 only the individual annidose animal ; considering what may 

 be inferred from its mode of evolution and final organization. 



