CHALK MAKERS, OR FORAMINIFERA. 35 



pseudopodia, nutrition may be supplied down to 

 the furthest chamber, by means of the minute threads 

 of communication, from the open mouth of the shell, 

 and the pseudopodia operating therefrom. 



We may regard the animal as of close kindred to, 

 although not absolutely the same, as an Amceba, from 

 which it differs in its pseudopodia, or voluntary ex- 

 tensions of the body, being thin delicate threads, 

 sometimes so thin as to be scarcely visible, and not 

 obtuse lobes ; and also in the absence of a nucleus. 

 For all practical purposes we may assume that it is 

 somewhat of an Amoeba, enclosed in a shell. And 

 here again we must apply a reservation, since at 

 certain times, if not always, the substance (or sarcode) 

 of the animal flows over and envelopes the whole 

 external surface of the shell, and hence, as Dr. Car- 

 penter observes, " it is by no means impossible that 

 the digestive process may really be performed in this 

 external layer, so that only the products of digestion 

 may have to pass into the portion of the sarcode 

 body occupying the cavity of the shell. A recog- 

 nition of this fact has led some writers to protest 

 against regarding the shell as a home constructed by 

 the animal to inhabit, since, as they affirm, it is a 

 skeleton built up within the body of the same ma- 

 terials, and in the same manner, as the bones of the 

 skeleton in a mammal. 



" The sarcode body of such Foraminifera as have 



D 2 



