GENERAL ORGANIZATION OF F OR AM INIF ER A, 



437 



several such apertures, though it is now more commonly under- 

 stood as applying to the sieve-like structure often presented by 

 the external shell. It was by M. Dujardin, in 1835, that the 

 structure of these animals was first shown to be conformable to 

 the Rhizopod type ; and notwithstanding the opposition to his 

 views which has been set up by Prof. Ehrenberg (who, with in- 

 explicable pertinacity, has con- 

 tinued to rank them among his Fw- 204. 

 Bryozoa, Chap. XIII), they have 

 been confirmed by all subse- 

 quent observers, and more espe- 

 cially by the recent researches 

 of Prof. Schulze,' who has given 

 admirable descriptions of the 

 animals of several different 

 kinds of Foraminifera, derived 

 from observation of them during 

 their living state. The confor- 

 mity of the Foraminifera to the 

 ordinary Rhizopod type, is best 

 seen in those forms, such as 

 G-romia (Fig. 204), in which 

 there is no multiplication of 

 chambers; and it is made ob- 

 vious by an examination of the 

 accompanying figure, that there 

 is no other essential difference 

 between G-romia and Arcella or 

 Diffugia (Fig. 193), than that 

 which lies in the greater length 

 and sleuderness of the pseudo- 

 podial prolongations of the sar- 

 code body in the former, as com- 

 pared with those of the latter. 

 The food is obtained by the ex- 

 tension of these pseudopodia in 

 various directions from the 

 mouth of the shell ; and the ab- 

 sence of any membrane investing them is clearly indicated by 

 their fusion or coalescence when two or more happen to come 

 into contact, as well as hj the vagueness of the expansions into' 

 which they are occasionally seen to spread out. These instru- 

 ments entangle and lay hold of the minute bodies which serve as 

 food to the animals, consisting of DiatomaccEe, Desmidiese, the 

 smaller forms of Confervse, &c. ; and they draw these, by their 

 contraction, into the substance of the body, within which they 

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

 means constantly, that their indigestible residua are cast forth 



' "tjber den Orgariisraus der Polythalamien (Foraminiferen).'' Leipzig, 1854. 



Gramia oviformis, with ils pseudopodia extended. 



