IN RELATION TO ORGANISED BEINGS. 39 



«ther characters so as to make the precise boundaries of a group 

 always difficult to determine, obliging us to consider not only typical 

 plans, but intermediate conditions, Avhere we have to judge which of 

 two or of several types predominates. All organized beings tend to 

 one of two plans of development, one of which has for its end the 

 sustentation of the individual or the race, the other intercourse with 

 external things by means of powers of sense and motion. The former 

 only is perceptibly manifested in the vegetable kingdom, the latter is 

 added in the animal kingdom ; but besides this great addition, little 

 perceptible in some of the lower forms of animals, the plan of nutrition 

 itself entirely differs in the two kingdoms and it is here that we find 

 the best marked distinctions. Vegetables are nourished by inorganic 

 matter, water with gases or salts dissolved in it ; animals by organised 

 substances, whether fresh or tending to decomposition, but not having 

 returned to their elements. This is the grand real distinction, but it 

 is at least very difficult of application in some of the lower forms. 



The simplicity and uniformity of the means of nutrition in the vege- 

 table kingdom leave us no such convenient means for distinction of 

 forms as are found in the animal. Hence we are obliged to rely for 

 characters on the mode and results of growth, and, to a very great 

 extent, on the reproductive system — and it follows that there can be 

 no real analogy between plans of classification in the two kingdoms, 

 nor any agreement otherwise than accidental in the number of divisions 

 produced — whilst within the animal kingdom the same variations in 

 the tendency of development which mark the primary divisions, acting 

 again under each secondary type produce a nearly uniform conformity 

 in the number of divisions at each step in our progress, and a conse- 

 quent analogy between all groups, larger or smaller, which occupy the 

 same position in the order of subdivision. This may also be the case 

 in the vegetable kingdom, but as we cannot yet characterise the ten- 

 dencies upon which our great groups depend, the analogies we trace 

 are there more slowly worked out and our progress towards a complete 

 classification is far less satisfactory. The earliest attempts at botanical 

 classification were, doubtless, intended to follow an order discernible 

 in nature ; but they were so rude in themselves, as well as so difficult 

 of application, that they afforded little assistance. Right ideas of the 

 uses, relations, and variations of the organs making up a structure, 

 necessarily precede the just perception of resemblances and differences, 

 ;and these are among the hard-earned acquisitions of modern science. 



