DISTINCTIVE CHARACTEES OF ORGANIZED BODIES. 19 



being the instrument of some special action or function, which. 

 it performs under certain conditions ; and the concurrence of 

 all these actions being necessary to the maintenance of the 

 structure in its normal or regular state. Hence there , is a 

 relation of mutual dependence among the parts of an Organized 

 fabric, which is quite distinct from that of mere proximity ; 

 and this relation is most intimate, not in the case of those 

 beings which have the greatest multiplication of parts, but 

 among those in which there is the greatest dissimilarity 

 among the actions of the several organs. Thus it has been 

 just shown that among Plants and Zoophytes, a small fraction 

 of an organism may live independently of the rest; the 

 necessary condition being that it shall either itself contain 

 all the organs essential to life, or shall be capable of pro- 

 ducing them, as when the leaf-bud develops rootlets for 

 its nutrition. This "vegetative repetition," and consequent 

 capacity of sustaining the loss of large portions of the fabric, 

 still shows itself in animals much higher in the scale than 

 Zoophytes ; thus it is not uncommon to meet with Star-fish 

 in which not only one or two, out of the five similar arms, 

 but even three or four, have been lost, without the destruction 

 of the animal's life ; and this is the more remarkable, as these 

 arms are not simply members for locomotion or prehension, 

 but are really divisions of the body, containing prolongations 

 of the stomach. In like manner, many of the Worm tribes, 

 whose bodies show a longitudinal repetition of similar parts, 

 can lose a large number of their joints without sustaining any 

 considerable damage. In the bodies of the higher animals, 

 however, where there are few or no such repetitions (save 

 in the two lateral halves of the body), and where there is, 

 consequently, a greater diversity in character and function 

 between the different organs, the mutual dependence of their 

 actions upon one another is much more intimate, and the loss 

 of a single part is much more likely to endanger the existence 

 of the whole. Such structures are said to be more highly 

 organized than those of the lower classes ; the principle of 

 " division of labour " being carried much further in them, 

 a much greater variety of objects being attained, and a much 

 higher perfection in the accomplishment of them being thus 

 provided for. Thus the individuality of a plant or a zoo- 

 phyte may be said to reside in each of its multiplied parts ; 



c2 



