xiv.] ORGANIC FUNCTIONS. 165 



NOTE A. 



We have seen that all organisms whatever have the power of Only vege- 



eflfecting chemical transformations in matter, but the power of ^^"^'^^ 



° ' ^ decompose 



decomposing carbonic acid and forming the primary organic com- carbonic 

 pounds belongs to vegetables alone. It is not, however, a correct ^ 

 account of the matter, to say that vegetables separate carbon 

 from the inoiganic world, and that the animals which eat the 

 vegetables give it back to the inorganic world again in the car- 

 bonic acid of their respiration. The truth is that the formation 

 of carbonic acid by respiration, which is a slow combustion, is a 

 function of all organisms whatever,^ and probably of every jaart All or- 



of every organism that continues to live (not of such tissues as g^'Uisms 



. ^ produce it. 



nails and hair). The opposite function of decomposing carbonic 



acid and assimilating the carbon, on the contrary, belongs no 

 doubt to vegetables only ; but it does not belong to every part 

 of a vegetable, nor to every vegetable species, nor to any vege- 

 table at all times (any air-breathing vegetable at least, for it 

 may be different with sea-weeds, the deep-growing species of 

 which are less dependent on light). The power of decomposing 

 carbonic acid does not belong to germinating seeds, for they give 

 off carbonic acid just like respiring animals. It belongs only to the Only the 

 green parts of plants, and to them only when exposed to light ; orveCTe^-' ^ 

 and there are tribes of plants that have no green parts, and do tables 

 not decompose carbonic acid at all, but obtain their carbon, like j^ and 

 animals, by feeding on other plants. Such are the fungi, which oiily in the 



obtain their carbon mostly from decaying vegetable matter ; and ,5" ' , , 



„ „ . " Vegetable 



also the Orobanchacese, a tribe of ilowermg but leafless plants tribes that 



which are parasitic on other plants, and live on their juices.'^ , ^°* 



^ • Ti -1 decompose 



If then vegetables have motor actions like animals, and if carbonic 



there are whole tribes of vegetables which, like animals, do not ^'^^*^^' 



decompose carbonic acid, and if the lowest classes of animals t ° ^^?°" 



have no muscles nor nerves, what is the distinction between the tinction 



kingdoms ? I reply, that I do not believe there is any absolute °®*^^Y*i^] 



and certain distinction whatever. and ani- 



mals. 



1 A possible exception to this is mentioned in note 2, p. 85. 



2 Carpenter's Comparative Physiology, p. 732. It is to be observed, 

 however, that the copper beech, and other plants with leaves that are 

 not green, decompose carbonic acid in the usual way. 



