26 COMPARATIVE ZOOLOGY. 



like an animal— a consumer, not a producer : not Mil the 

 young shoot rises above the soil, and unfolds itself to the 

 light of the sun, at the touch of whose mystic rays chloro- 

 phyl is developed, does real, constructive vegetation be- 

 gin ; 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.' 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." Be- 

 sides this internal movement, myriads of plants, as well 

 as animals, are locomotive. Rambling Diatoms, writhino- 

 Oscillaria, and the agile spores of Cryptogams crowd our 

 waters, their organs of motion (cilia) being of the very 

 same character as in microscopic animals; while Spono-es, 

 Corals, Oysters, and Barnacles are stationary. A contrac- 

 tile vesicle is not exclusively an animal property, for the 

 fresh-water Volvox and Gonium have it. The muscular 

 contractions of the highest animals and the sensible mo- 

 tions of plants are both due to changes in the protoplasm 

 in their cells. The ciliary movements of animals and of 

 microscopic plants are precisely similar, and in neither 

 case indicate consciousness or self-determining power. 



