24 DISTINCTIVE CHAEACTERS OF ANIMALS. 



and excretion, of the effete matters with, which the blood be- 

 comes charged by the decomposition continually going on in 

 the body ; the maintenance of animal-heat by the same process ; 

 and the act of reproduction, whereby the race is perpetuated, 

 in spite of the limited duration of the individual. The fore- 

 going, which are for the most part common to the Animal and 

 the Plant, are termed Organic Functions, or Functions of 

 Vegetative Life. But, in addition to these, it is the character- 

 istic of Animals generally, that they are sensible to impressions 

 made by surrounding objects, so that they possess some con- 

 sciousness of what is going on about them ; and that they also 

 possess the power of re-acting on those objects by movements 

 of their own, so as to change either their own places, or 

 the places of surrounding objects in relation to them- 

 selves. These two functions, sensibility and the power of 

 spontaneous motion, being peculiar to animals, are distin- 

 guished as Animal Functions, or Functions of Animal Life. In 

 the higher, animals, they are the most important and charac- 

 teristic phenomena of their existence ; so that it would seem 

 as if the whole assemblage of organic functions had no other 

 destination in them, than to build up and keep in order the 

 apparatus by which the functions of animal life are performed. 

 But this state of things is entirely reversed among those 

 lower tribes of animals which border most closely on the 

 Vegetable kingdom ; for we find that among such, the mani- 

 festations of sensibility and power of spontaneous movement 

 are so feeble, that it may be doubted whether these attributes 

 are really present in them ; and even in higher orders, there 

 are many in which the proper animal powers are in such a 

 low grade of development, that they appear as if they were 

 destined merely to minister to the organic functions. 



7. Thus, although the characteristic difference between the 

 Animal and the Vegetable kingdom, taking each as a whole, 

 may be truly said to consist in the possession by the former 

 of endowments which do not exist in the latter, this does not 

 express the essential difference between Animals and Plants ; 

 since, while there are many tribes among the former in which 

 the proper animal powers are reduced to so low a degree as 

 to prevent it from being certainly affirmed that they are 

 present at all, there are many tribes among the lower plants 

 which exhibit a power of spontaneous movement fully as 



