28 



INYEliTEBKATE ANIMALS. 



As regards the functions of relation, it is questionable how far the 

 Amoeba can be said to liave distinct percejitionn or sensations »i any 

 kind. It has no ncivous .system or organs of sight or hearing, and 

 in all prob.iliility it has nothing more than a general sensibility to 

 light. It appears, however, to be fully aware when any object 

 comes in contact witli a pseud(i])odium, and even to have some idea 

 whether this is tit for food. Locomotion, 

 as we have seen, is entirely effected by the 

 temporary processes of sarcode, or pseudo- 

 podia, and there are no permanent organs 

 set aside eitlier f(jr locomotion or for pre- 

 licnsion — that is, for seizing external 

 objects. 



Many other Ehizopods, more or less 

 closely related to the Amceha, have been 

 descrilied. Some of these, though resem- 

 bling the Ama'ia in general structure, and 

 in the form of the pseudopodia, have the 

 Soft ]iri>toplasniic br)dy enclosed in a kind 

 of shell or "test." A good example of 

 these shelled Am(jebea\s, the little Di^vgia 

 (llg. 7), a not uncommon iidiabitant of 

 fie ill water. In this form the body is 

 enclosed in a siirt of .shell, composed of 

 sand -grains and other foreign particles 

 cemented together by a kind of horny 

 secretion. Tlie animal can retire within 

 its shell, one end of which is open, so as 

 to allow of the ]>rotrusioii of the pseudo- 

 ]>odi;i. In walking, the animal creeps 

 about "head-downwards," so to speak — 

 that is to say, witli the closed end of the 

 shell elevated abi>\e the surfiic" on which it is movinar. 



'ig. -. — IltlJIu'liu i.iii,j,.ii„,s, 

 greatly ciilarffd. (Altii.d 

 slightly finiiL Cirtcv.) Tlic- 

 case is r()iii]i(isc(l (if :iii,i;iiliii' 

 ^n'aiiis n[' ti;nis]iari'iit ijiiaitz, 

 IvitliilL wliieli is tlie tral,s|,,i- 

 liTit iiiil.T liiyiTct tlie lioily, 

 liiipil Ijy til.' liiicly ^n;niul.ir 

 inner Layer ; e Nneleiis ; e e 

 Cuntraetile vesicles. 



OllDER III. F()RAMI.\IFER.\. 



The next order of the Illij-ji/inil,! is that of the Foraminifera, com- 

 prising aiiini.-ds which .it hist sight .appear to be highly complex, but 

 which are re.'iHy less highly organised than the Amo'ha. The Ford- 

 viinifi'rii may be di-tineil as l!lii:i>pi)ihi in ir/iii-h tlu' Ixuh/ is proteftnl 

 1,11 a xIh'JI III- '"test" ; II. niir/i'iix iiml cnntnirtile rrxir/i' lire vsiiaUi/ 

 /iri-si'ii/. ; mill tin- iixriiiliiiiiiiilu ,ire i.itn'iiirjif lunij mid tliread-lihe, and 

 iiitrrhirr iritli iiiii; iiiiiiihi'r xij 11.1 to fiirin a iniinirk. 



The most olivious and stiiking character of the Forami/iifcni is 



