19 



CHAPTEK III 



THE STRUCTURE AND REPRODUCTION OF THE 

 FORAMINIFERA {Rhizopoda reticular la) 



Structure. — Foraminifera differ from the lobose 

 rhizopods, such as Anvrha., not only in the form of 

 their sarcode prolongations or pseudopodia, but in 

 having an investing shell or test composed of car- 

 bonate of lime, of cemented sand-grains, sponge 

 spicules, and other adventitious particles, or of 

 chitin. It is true that some of the lobose forms 

 possess a covering, or lorica, but these are excep- 

 tional, and in the case of Arcella it is merely a scale- 

 like chitinous shield. Diffluyla also bears some 

 resemblance to the monothalamous (single-cham- 

 bered) forms of lieoplui.r, but the former genus is 

 essentially of fresh-water habit. 



The body substance of Foraminifera consists of 

 protoplasm or sarcode, generally transparent and 

 nearly colourless, but sometimes of a pale brownish, 

 pink, or violet tint. The animal is usually divided 

 into more or less numerous segments, each of which 

 is separated from the adjacent one by a septal shell- 

 wall, and which are connected with one another by 

 slender filaments of sarcode, called stolons, which 

 pass through the foramina of the septum. 



To gain an adequate idea of the appearance of 



c2 



