132 BIOLOGY. [Book n. 



fed bees exclusively upon honey, obtained thus an overplus 

 of wax.' 



Whatever may be their source, the fatty matters of the 

 economy, when in excess, are deposited in the meshes of the 

 cellular tissue, and generally in the larges quantity where 

 the organic activity is the least. 



3. — Albumindidal Substances. 



Are proteic substances completelyformed,by chemical synthesis, 

 in the economy? That is possible, but not suflSciently proved. 

 It is most probable that the albuminoidal substances of the 

 anatomical elements are derived by means of multiple isomeric 

 elaborations and modifications from the compounds of the same 

 kind existing in the aliments. These substances the inferior 

 animals, without differentiated anatomical systems, absorb direct 

 from the ambient medium ; the other kinds of animals find 

 them already prepared in other organisms. According to a 

 general formula, which has for a long time found acceptance, 

 it is the vegetal kingdom which is forced to provide for the 

 animal kingdom. We have seen that probably the marine 

 fauna forms an important exception to this formula, which is 

 correct as regards a very large majority of the terrestrial 

 animals. 



But, finally, whether the first origin of organic substances be 

 vegetal or animal, it is not the less true that the least complex 

 animal has need to borrow from other organisms non-mineral 

 aliments, without which it cannot live. If, as we have just 

 seen, the fact may in a certain degree be contested as regards 

 the albuminoidal and saccharine compounds, it is undeniable in 

 regard to the more important materials of living beings, the 

 proteic substances. 



The animal never either absorbs or assimilates directly these 

 substances; it is necessary that they should undergo, before 

 ^ Comptes Bendus de VAcadimie des Sciences, 1843, t. xvii. p. 531. 



