26 



COMPARATIVE ZOOLOGY. 



rophyl is created, does real, constructive vegetation begin ; 

 then its mode of life is reversed — carbon is retained and 

 oxygen set free. 



Most plants, and many animals, multiply by budding 

 and division; on both we practise grafting; in both the 

 cycle of life comes round again to the ovule or ovum. 

 Do annuals flower but to die? Insects lay their eggs in 

 their old age. 



Both animals and plants have sensibility. This is one 

 of the fundamental physiological properties of proto- 

 plasm. But in plants the protoplasm is scattered and 

 buried in rigid structures : feeling is, therefore, dull. In 

 animals, the protoplasm is concentrated into special or- 

 gans, and so feeling, like electricity rammed into Leyden 

 jars, goes off with a flash. 8 Plants never possess conscious- 

 ness or volition, as the higher animals do. 



The self-motion of animals and the rooted state of plants 

 is a very general distinction ; but it fails where we need it 

 most. It is a characteristic of living things to move. The 

 protoplasm of all organisms is unceasingly active. 9 Be- 

 sides this internal movement, myriads of plants, as well 

 as animals, are locomotive. Rambling Diatoms, writhing 

 Oscillaria, and the agile spores of Cryptogams crowd our 

 waters, their instruments of motion (cilia) being of the 

 very same character as in microscopic animals ; while 

 Sponges, Corals, Oysters, and Barnacles are stationary. 

 A contractile vesicle is not exclusively an animal prop- 

 erty, for the fresh - water Volvox and Gonium have it. 

 The act of muscular contraction in the highest animal is 

 due to the same kind of change in the form of the cells of 

 the ultimate fibrillse as that which produces the sensible 

 motions of plants. The ciliary movements of animals 

 and of microscopic plants are precisely similar, and in 

 neither case indicate consciousness or self - determining 

 power. 



