THE PLANT AND THE ANIMAL 277 



albuminoids and then absorbed them as food, every one 

 would certainly have believed that we meant an animal 

 of soipe kind ; yet all these features would have been 

 those of very distinct and typical plants. If the nutrition 

 of plants can thus so closely resemble the nutrition of 

 animals, perhaps the nutrition of animals, on the other 

 hand, will never present us with a parallel to the pheno- 

 menon, which is characteristic of plants, of nutrition 

 at the expense of inorganic substances. But neither 

 can this be maintained, the property of decomposing 

 carbonic acid being, as we have seen, peculiar to a 

 special organ, namely the chloroplast, and we can name 

 several animal organisms containing chlorophyll.^ 



Now let us proceed to another supposed distinction 

 based upon the process of respiration. When the 

 interchange of gases taking place in plants, and resulting 

 in the decomposition of carbonic acid and the accumula- 

 tion of carbon, was erroneously com.pared to respiration, 

 the following antithesis used to be brought forward : the 

 respiration of animals consists in the absorption of 

 oxygen and the giving off of carbonic acid ; the respira- 

 tion of plants — in the absorption of carbonic acid and 

 the giving off of oxygen. We now know, however, that 

 the decomposition of carbonic acid cannot be compared 

 to respiration, that this is a case of nutrition — a peculiar 

 kind of nutrition by means of air ; we also know that 

 another process takes place simultaneously — real respira- 

 tion, but that this latter process can be observed only 

 when we investigate either colourless organs, or green 

 organs in the absence of light when the opposite process 

 of decomposition does not take place. This process of 

 respiration will certainly appear sluggish if compared 

 with the respiration of a mammal, or a bird. Carbonic 

 acid is given off in great quantities by the latter, and the 

 resulting rise of temperature above the temperature of 



^ This chlorophyll belongs, however, probably to algae which have 

 f ouad their way into the animal organisms in question. 



