8 PEOTOZOA. 



can be protruded through the numerous apertures in the periphery of 

 the shell in the shape of long contractile filaments (pseudopodia). 



(18.) On removing the delicate calcareous shell by the assistance of 

 a weak acid, the body of the animal denuded of its covering (fig. 2, 2) 

 is found to be entirely soft : that portion which is lodged in the first 

 compartment of the shell is colourless and of a crystalline transparency ; 

 but in each of the succeeding segments there may be detected a granu- 

 lar mass of a brownish colour, and not unfrequently the minute silicious 

 shells of Naviculce, Barillarice, and other forms of Infusorial organisms, 

 the remains of which may be traced nearly as far as the umbilicus of 

 the spiral. 



(19.) The pseudopodia of the Foraminifera probably entangle and 

 lay hold of the minute bodies which serve as food, consisting of Diato- 

 maceee, Desmidiese, the smaller forms of Conferva^ &c., and draw these 

 by their contraction into the substance of the animal, within which they 

 may be seen through the transparent shell. It is not by any means 

 constantly that their indigestible residua are cast forth again, for they 

 sometimes accumulate in such numbers as even to choke up a con- 

 siderable part of the cavity. The living gelatinous substance is occa- 

 sionally seen to extend itself around the exterior of the shell ; and 

 pseudopodia may then be put forth from this extension as well as from 

 the ordinary outlets. 



(20.) The Eoraminifera are evidently composite fabrics evolved by a 

 process of continuous gemmation, each gemma remaining in connexion 

 with the body by which it was put forth ; and according to the plan on 

 which this gemmation takes place will be the configuration of the 

 shell. Thus, if a bud should be put forth from one of these creatures 

 in the direction of the axis of its body, and a second shell should be 

 formed around this bud in continuity with the first, and this process 

 should be successionally repeated, a straight rod-like shell will be pro- 

 duced, having many chambers communicating with each other by the 

 openings that originally constituted their mouths, the mouth of the last- 

 formed chamber being the only aperture through which the gelatinous 

 body, thus composed of a number of segments connected by pedicles or 

 stolons of the same material, can receive a supply of food. The succes- 

 sive segments may be all of the same size, or nearly so, in which case 

 the entire rod will approach the cylindrical form, or resemble a line of 

 beads ; but it often happens that each segment is somewhat larger than 

 the preceding, so that the composite shell has a conical form, the apex 

 of the cone being the original segment, and its base the one last pro- 

 duced. If each of the successively formed segments instead of being 

 developed exactly in the axis of its predecessor should be directed a 

 little to one side, it is obvious that a curved instead of a straight rod 

 will be the result ; and this curve may be increased until it become a 

 spiral. The character of this spiral will depend in a great degree upon 



