SECT, ii. THE GROMI^E. 27 



take part in the general movement. In the broader 

 filaments two currents carrying particles pass backwards 

 and forwards in opposite directions at the same time, 

 and the network in which these motions are going on 

 is undergoing continual changes in its arrangements. 

 New filaments are put forth, sometimes from the midst 

 of the ramifications, while others are retracted; and 

 occasionally a new centre of radiation is formed at a 

 point where several threads meet. The food consists of 

 diatoms and morsels of vegetable matter ; but the 

 Gromise have no vent, so that the indigestible matter 

 collects in a heap within them. However, as the form of 

 the test is such that the animal cannot increase its size, 

 it leaves it when it becomes too small for its comfort 

 and forms another, and it is supposed to get rid of the 

 effete matter at the same time. The Gromise have no 

 nucleus or contractile vesicle. 



CLASS II. FORAMINIFERA. 



The geological importance of the Foraminifera, their 

 intrinsic beauty, the prodigious variety of their forms, 

 their incredible multitude, and the peculiarity of their 

 structure, have given these microscopic organisms the 

 highest place in the class of Ehizopods. The body of 

 these animals consists of a perfectly homogeneous 

 sarcode or semi-fluid protoplasm, showing no tendency 

 whatever to any film or surface-layer. It is inclosed 

 in a shell ; and the only evidence of vitality that the 

 creature gives, is a protrusion and retraction of slender 

 threads of its sarcode, through the mouth or pores of 

 the shell, or through both according to its structure. 

 Fig. 97 shows some of their forms. 



By far the greater number of the Foraminifera are 

 compound or many-chambered shells. When young, 

 the shell has but one chamber, generally of a globular 



