214 THE DAWN OF LIFE. 



buds in tlie plant. The Polyps and complex Bryozoons 

 present a higher and more specialised type; and though 

 the bilateral symmetry which obtains in the higher 

 animals is of a different nature^ it still at least reminds 

 us of that multiplication of similar parts which we see 

 in the lower grades of being. It is worthy of notice 

 here that the lower animals which show aggregative 

 tendencies present but imperfect indications, or none 

 at all, of bilateral symmetry. Their bodies, like those 

 of plants, are for the most part built up around a 

 central axis, or they show tendencies to spiral modes 

 of growth. 



It is this composite sort of life which is connected 

 with the main geological function of the Foraminifer. 

 While active sensation, appetite, and enjoyment per- 

 vade the pseudopods and external sarcode of the mass, 

 the hard skeleton common to the whole is growing 

 within; and in this way the calcareous matter is 

 gradually removed from the sea water, and built up 

 in solid reefs, or in piles of loose foraminiferal shells. 

 Thus it is the aggregative or common life, alike in 

 Foraminifers as in Corals, that tends most powerfully 

 to the accumulation of calcareous matter; and those 

 creatures whose life is of this complex character are  

 best suited to be world-builders, since the result of ^ 

 their growth is not merely a cemetery of their osseous 

 remains, but a huge communistic edifice, to which 

 multitudes of lives have contributed, and in which 

 successive generations take up their abode on the 

 remains of their ancestors. This process, so potent in 



