PROTOZOA. 271 



be separated into two divisions those in which the cells 

 are large, the regularity of their arrangement visible, and 

 their bond of union consists of a single constructed por- 

 tion between each ; and those in which the cells are 

 minute, not averaging more than the 900th part of an 

 inch in diameter, the regularity of their arrangement not 

 distinctly seen, and their bond of union consisting of many 

 thread-like filaments. To ascertain the mineral composi- 

 tion of the amber- coloured particles or casts, after having 

 found that it was mostly carbonate of lime with which they 

 were surrounded, they were placed for a few moments in the 

 reducing flame of a blow-pipe, and it was observed that on 

 subsequently exposing them to the influence of a magnet, 

 they were all attracted by it. Hence, in a rough way, this 

 rock may be said to be composed of carbonate of lime and 

 oxide of iron. 



Truthfully does Lamarck say of the Foraminifera, 

 " Their smallness renders their bodies contemptible to our 

 eyes ; in fact, we can hardly distinguish them ; but we 

 cease to think thus when we consider that it is with the 

 smallest objects that nature produces the most imposing 

 and remarkable phenomena. Now, it is here again that 

 we have one of the numerous instances which attest that, 

 in her production of living bodies, all that nature appears 

 to lose on one side in volume, she regains on the other 

 in the number of individuals, which she multiplies to 

 infinity." 



Eecent Foraminifera present symmetrical shells, of 

 minute size for the most part, of various patterns, and 

 consisting either of a single chamber or of two or more 

 connected chambers. A jelly-like mass, or "sarcode," 

 occupies the chambers and their connecting passages j and, 

 protruding itself both from the external aperture of the last 

 chamber, and in many cases from the sometimes numerous 

 perforations in the shell- walls, extends itself not only over 

 the surface of the shell, but also into radiating contractile 

 threads or pseudopodia, and into gemmule-like masses, 

 which latter become coated over with calcareous matter, 

 and thus form additional segments of the animal. 1 



(1) Among the more important works on Foraminifera, reference may be 

 made to D'Orbigny's Foraminiferes fossiles du Bassin Tertiaire de Vienna 



