1022 ANIMAL DIGESTION. 



to the plant, divide themselves into products admitting of 

 assimilation ; into fibrin, albumen, casein, and oily bodies, which 

 serve to increase or renew the organs ; and into combustible pro- 

 ducts, sugar and the oily bodies, which are consumed in respira- 

 tion. An animal thus assimilates, or destroys ready formed organic 

 matters ; it creates nothing.' 5 



Although the usual function of plants is to act, under the 

 influence of the solar rays, like apparatus of reduction, in which 

 water, carbonic ^acid and ammonia are decomposed, yet in some 

 circumstances, they act differently and more like animals. In 

 the germination of the seed, much heat is produced, with the 

 formation of carbonic acid and water. The starch of grain in 

 malting is observed to pass first into gum, then into sugar, and 

 lastly to disappear, producing carbonic acid. Sugar thus seems 

 to be the agent, by means of which plants as well as animals 

 develope the heat they require. The fecundation of plants is 

 always accompanied by heat, the flowers respiring and producing 

 carbonic acid. They must, therefore, consume carbon; and 

 accordingly we find that the sugar in the stems of the sugar- 

 cane has entirely disappeared after the flowering and fructifica- 

 tion are completed. The shot beet, turnip and carrot con- 

 tain no longer a trace of sugar in their roots. The oils accumu- 

 lated in some seeds appear to serve, like the fat of animals, to 

 support this respiration, and to supply the heat, by their 

 combustion, which plants require at certain periods of their 

 growth, and for the discharge of certain functions. 



The curious observation has also been made by M. Morren, 

 that certain green animalculae found in stagnant water, perform 

 the usual function of the green parts of vegetables, decomposing 

 carbonic acid and evolving oxygen, under the influence of the 

 light of the sun. The proportion of free oxygen in the water 

 is frequently raised, by their action from 30 to 56', or 5?, 

 or even to 61 per cent, while carbonic acid disappears in a 

 corresponding proportion. It is in the enchelide monad, (of 

 Bory,) only, and some other green animalcuke higher in the 

 series, that this phenomenon is observed.* 



*Ann. cle Cbim. etde Phys. 3 scr. 1. 456. 



