now THE ANIMAL MVES 231 



are to reprodiiec tlioir kiuil aii<l kocp up tho 

 fiitinv ln'nl, a iinxlcratt' aiiKHiiit of iiiiisciilai- 

 exerc'iso is as important as suitaldi.' tood ami 



4*J(). Tho animal body is a very complex 

 organism, with an almost endless variety of parts 

 and funotions, each of which is more or less 

 essential to the full nsffulnt'ss of tlM» whole. The 

 best conditi(jn of bodily liealtli is that in which 

 all of these are properly adjusteil to eaeh other 

 and to the surroundini^s. In the case of fai-m 

 animals, the eomplexity is the j^reater beeanse the 

 natural functions must be developed heic and 

 restricted there, to make them a i>ro(itable p(xs- 

 session ; and all this imist b«> done within limits 

 which will b«» compatil)le with the niaintenanee of 

 health and vii^^or. 



SI (.(iKSTin.xs o.y cnxriHU v/r 



359<i. Th«> lH*Ht illiiHtrtttion which thi* pupil eiiii Sfoiiro of a 

 Hinjfle-rt'llrd Htnu'tur«'I»«,H orpnniHm is Ww aniii>l>n ( Fifj. 81). 

 This lowly anininl livi-s in stiiK'iinnt pools, nixl fiin Im« Hi'ctireil 

 by flcrapinf; the scum off tho stctiis and li>avt'H of watrr plantn. 

 In \ia lar(;or forms it ia barofy visible to the naked eye. 



3596. The Fip. 85 fihowa a spindle-»hnped ( involuntary) con- 

 tmctile cell or fllwr from the muHoular layer of tho intestine, 

 ■howinfr nucleus in white and nucleolus in black. It has no 

 iuch variety of functions as the an]a<ba has. 



3C0(i. A part or an orjjanism is said to he sp«>ciali7.ed when 

 it is fitted for some particular work, rather than for fffncral 



