8 ANIMALS CONTRASTED 



any other, the case would be different, and we should 

 justly call a being exhibiting such motion, an animal. 

 But low down in the scale of life, where alone there exists 

 any difficulty in distinguishing the two classes, movements, 

 although almost always more lively, are scarcely or not at 

 all more purposive in one than the other ; and even if we 

 decide on the animal nature of a being, it by no means 

 follows that we are bound to acknowledge the presence of 

 sensation or volition in the slightest degree. There may 

 be at least no evidence of its possessing a trace of those 

 tissues, nervous and muscular, by which, in the higher 

 members of the animal kingdom, these qualities are mani- 

 fested. Probably there is no more of either of them in 

 the lowest animals than in vegetables. In both, movement 

 is effected by the same means ciliary action, and hence the 

 greater value, for purposes of classification, of the power 

 to live on this or that kind of food, on organic or inorganic 

 matter. As the main purpose of the lowest members of 

 the vegetable kingdom is doubtless to bring to organic 

 shape the elements of the inorganic world around, so the 

 function of the lowest animals is, in like manner, to act on 

 degenerating organic matter, "to arrest the fugitive 

 organized particles, and turn them back into the ascending 

 stream of animal life." And, because sensation and voli- 

 tion are accompaniments of life in somewhat higher animal 

 forms, it is needless to suppose that these qualities exist 

 under circumstances in which, as we may believe, they 

 could be of no service. It is as needless as to dogmatise 

 on the opposite side, and say that no feeling or voluntary 

 movement is possible without the presence of those tissues 

 which we call nervous and muscular. 



The presence of a stomach is a very general mark by 

 which an animal can be distinguished from a vegetable. 

 But the lowest animals are surrounded by material that 

 they can take as food, as a plant is surrounded by an 

 atmosphere that it can use in like manner. And every part 



