THE LOWEST GBADE OF LIFE. 409 



not only this, but in many instances forming shelly coverings 

 of a symmetry and complexity not surpassed by those of any 

 testaceous animals,"* whilst the mere separation of a frag- 

 ment of this jelly is sufficient to originate a new and inde- 

 pendent organism, so that any number of these beings may 

 be produced by the successive detachment of such particles 

 from a single Rhizopod, each of them retaining (so far as we 

 have at present the means of knowing) the characteristic en- 

 dowments of the stock from which it was an offset. 



When, on the other hand, we watch the evolution of any 

 of the higher types of Organization, whether vegetable or 

 animal, we observe that although in the first instance the pri- 

 mordial cell multiplies itself by duplicative subdivision into 

 an aggregation of cells, which are apparently but repetitions 

 of itself and of each other, this homogeneous extension has 

 in each case a definite limit, speedily giving place to a struc- 

 tural differentiation, which becomes more and more decided 

 with the progress of development, until in that most hetero- 

 geneous of all types the Human Organism no two parts are 

 precisely identical, except those which correspond to each 

 other on the opposite sides of the body. With this structural 

 differentiation is associated a corresponding differentiation of 

 function ; for whilst in the life of the most highly developed 

 and complex organism we witness no act which is not fore- 

 shadowed, however vaguely, in that of the lowest and sim- 

 plest, yet we observe in it that same " division of labour " 

 which constitutes the essential characteristic of the highest 

 grade of civilization. For, in what may be termed the ele- 

 mentary form of Human Society, in which every individual 

 relies upon himself alone for the supply of all his wants, no 

 greater result can be obtained by the aggregate action of the 

 entire community than its mere maintenance ; but as each in- 



* See the Author's Introduction to the Study of the Foramimfera, pub- 

 lished by the Ray Society, 1862 : Preface, p. vii. 

 18 



