408 CORRELATION OF PHYSICAL AND VITAL FORCES. 



Now the difference between a being of high and a being 

 of low organization essentially consists in this : that in the 

 latter the constituent parts of the fabric evolved by the pro- 

 cess of growth from the original germ, are similar to each 

 other in structure and endowments, whilst in the former they 

 are progressively differentiated with the advance of develop- 

 ment, so that the fabric comes at last to consist of a number 

 of organs, or instruments, more or less/ dissimilar in struc- 

 ture, composition, and endowments. Thus in the lowest 

 forms of Vegetable life, the primordial germ multiplies itself 

 by duplicative subdivision into an apparently unlimited num- 

 ber of cells, each of them similar to every other, and capa- 

 ble of maintaining its existence independently of them. And 

 in that lowest Rhizopod type of Animal life, the knowledge 

 of which is among the most remarkable fruits of modern bio- 

 logical research, " the Physiologist has a case in which those 

 vital operations which he is elsewhere accustomed to see car- 

 ried on by an elaborate apparatus, are performed without any 

 special instruments whatever ; a little particle of apparently 

 homogeneous jelly changing itself into a greater variety of 

 forms than the fabled Proteus, laying hold of its food without 

 members, swallowing it without a mouth, digesting it without 

 a stomach, appropriating its nutritious material without absorb- 

 ent vessels or a circulating system, moving from place to place 

 without muscles, feeling (if it has any power to do so) with- 

 out nerves, propagating itself without genital apparatus, and 



and Animals, especially the Fungi and Entozoa similar germs may devel- 

 op themselves into very dissimilar forms, according to the conditions un- 

 der which they are evolved ; but such diversities are only the same kind as 

 those which manifest themselves among individuals in the higher Plants and 

 Animals, and only show that in the types in question there is a less close 

 conformity to one pattern. Neither in these groups, nor in that group of 

 Foraminifera, in which I have been led to regard the range of variation 

 as peculiarly great, does any tendency ever show itself to the assumption 

 of the characters of any group fundamentally dissimilar. 



