242 ELEMENTS OF SCIENCE 



muscular tissue such a condition we find in the hydra. 

 The vegetable kingdom advances in complexity in a 

 quite diverse mode, building up a variously branching 

 axis with foliar organs (modified leaves), but always 

 devoid of any alimentary cavity and any form of muscu- 

 lar or nervous tissue. 



The functions which are peculiar to the higher organ- 

 isms, and are exhibited by all living creatures which 

 possess nervous and muscular tissue, are (as has been 

 before said) those of movement and feeling. These two 

 functions are distinguished as the functions of animal life, 

 in contradistinction to the functions of nutrition and 

 reproduction, which, being possessed by all plants, as 

 well as animals, are termed the vegetative functions. 

 That the animals with which we are most familiar have 

 feelings and emotions, and that we can, to a considerable 

 extent, tell what these are, hardly any one will be dis- 

 posed to deny. As to lower animals, the complex social 

 economy of bees is a matter of common knowledge. 

 Ants display a complete and yet more complex 

 political organisation. Some have soldiers which cap- 

 ture slaves, while other kinds will retain other insects 

 (Aphides*) captive to serve a purpose analogous to that 

 of our milk -giving cattle. 



We have already spoken of the vocal and gesture 

 language of the cat. Pointers and setters will make 

 certain facts known by their gestures; the songs of 

 birds have meanings practically understood by their 

 fellows, while parrots and jackdaws can learn to articu- 

 late whole sentences. 



As to the mental faculties of the higher animals, they 



* The small slow-moving green flies so common on rose trees 

 and pelargoniums. 



