THE DAWN OF LIFE 1 77 



sand cemented together. These coverings are 

 always perforated with at least one orifice for the 

 emission of the thread-like processes or pseudopods, 

 and often with a vast number of small pores for 

 the same purpose. Sometimes the test or shell is 

 smooth, sometimes beautifully sculptured exter- 

 nally. Sometimes it consists of a single chamber 

 like a ball or vase. More often, as the animals 

 increase in size, they form additional chambers, 

 and the body thus becomes divided into lobes 

 connected with each other by necks passing through 

 orifices in the partitions. The chambers are ar- 

 ranged in rows or in spirals, and in other ways^ 

 giving a vast variety of forms, often presenting the 

 most beautiful patterns executed in the purest 

 white marble, and the ornamental parts constitute 

 thickenings of the walls giving greater strength, and 

 are penetrated with microscopic canals communicat- 

 ing with the soft substance of the animal. 



These creatures abound in all parts of the ocean, 

 from the surface to the greatest depths. The 

 Foraminifera have also existed from the earliest 

 geological times, and in all the long ages of the 

 earth's history seem to have retained the same 

 structures and even ornamentation ; so that species 



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