128 



LEISURE-TIME STUDIES. 



soft, semi-fluid body. The neighbour-particle we name a 

 radiolarian (Fig. n), existing side by side with the fora- 

 minifer, selects flint as its special material from its native 

 waters, and builds a shell of this substance, exhibiting in many 



FIG. 10. Shells of foraminifera, all magnified : a, Lagcna, or "flask animalcule ;" 

 b, Discorbina ; c, Polystomclla. 



cases, outlines of mathematical nature, and shapes of the 

 most graceful and elegant kind. Thus there must exist, even 



FIG. ii. A radio- 

 larian shell (Podocyrtis). 



FIG. 12. A living foraminifer (Rota.Ha), showing the living 

 matter protruded from the shell. 



in such simple and primitive organisms, not only a selective 

 principle of the exact nature of which we are utterly ignorant, 

 but a further exercise, in the building of a shell, of a power 

 of whose exact direction and extent we know absolutely 

 nothing. 



