112 



MORPHOLOGICAL DEVELOPMENT. 



present us only with aggregates of the second order, that 

 have in many cases become very large and very complex. 

 We find in them no trace of the union of gemmiparously- 

 produced individuals. Neither the molluscous nor the 

 vertebrate animal shows the faintest trace of a segmenta- 

 tion affecting the totality of its structure ; and we see 

 good grounds for concluding that such segmentation as ex- 

 ceptionally occurs in the one and usually occurs in the other, 

 is superinduced. 



