ANIMALS AND PLANTS 197 



chiefly directed upwards and downwards, and that this is the reason 

 of the peculiar shape and arrangement of these living bodies, in short, 

 of their ascending and descending vegetation. From this it follows 

 that the canals, in which move the essential fluids of these bodies, 

 are parallel to one another and to the longitudinal axis of the plant ; for 

 it is always parallel, longitudinal tubes that are formed in their cellular 

 tissue, and these tubes do not diverge except to form the flattened 

 expansions of leaves and petals, or to be distributed in the fruit. 



Nothing of all this is found in animals. The longitudinal axis of 

 their bodies is not necessarily directed towards the sky, on the one 

 hand, and the centre of the earth, on the other hand ; the force wliich 

 stimulates their vital movements does not work exclusively in two 

 directions ; lastly, the internal canals which contain their visible 

 fluids are turned about in various ways and present no sort of 

 parallelism. 



The food of plants consists only of the liquid or fluid substances 

 which they absorb from the environment : this food includes water, 

 atmospheric air, caloric, Ught, and various gases which they decom- 

 pose and convert to their own use ; hence they never have to carry 

 on digestion, and for this reason they have no digestive organs. Seeing 

 that living bodies themselves elaborate their own substance, it is they 

 which form the first non-fluid combination. 



Most animals, on the contrary, feed on substances which are already 

 compound and which they introduce into a tubular cavity suitable 

 to receive them. Hence they have a digestion in order to bring about 

 the complete solution of these substances ; they modify existing 

 combinations and load them heavily with new principles ; so that it 

 is they which form the most complex combinations. 



Lastly, the final residue of destroyed plants is very different from 

 that which emanates from animals, showing that these two kinds of 

 living bodies are indeed of an entirely distinct nature. 



In plants, as a matter of fact, solids exist in larger proportion than 

 fluids, mucilage constitutes their softest parts, and carbon predomi- 

 nates among their component principles ; whereas in animals fluids 

 are more abundant than solids, gelatine abounds in their soft parts 

 and even in the bones of such as have any, while among their com- 

 ponents nitrogen is specially conspicuous. 



Moreover, the strata formed out of the residue of plants is chiefly 

 argillaceous and often contains silica, whereas those formed from 

 animals consist either of the carbonate or phosphate of lime. 



