52 ANIMAL CHEMISTRY LECTURE III. 



bodies, deoxidation, as manifested in the vegetable kingdom, 

 tends to the combination of atoms, or to the formation of complex 

 bodies out of simple ones. Now, the chemist in his laboratory 

 can imitate, however crudely, this synthesis of nature. We find 

 in the laboratory, as in the organism, that deoxidation, actual or 

 potential, leads to the conjunction of atoms, and to the building 

 up of complex molecules. In broad antagonism to the doctrines 

 which only a few years back were regarded as indisputable, we 

 now find that the chemist, like the plant, is capable of producing 

 from carbonic acid and water a whole host of organic bodies, 

 and we see no reason to question his ultimate ability to reproduce 

 all animal and vegetable principles whatsoever. 



(52.) But for the production of certain organic principles, 

 whether by natural or artificial means, something more than car- 

 bonic acid and water is required. The albuminoid bodies, in 

 particular, cannot be formed without nitrogen, and plants, in 

 general, cannot grow without a supply of ammonia or some 

 transformable compound. You will observe, however, that 

 ammonia, considered as a pabulum for plants, differs in this 

 important respect from both carbonic anhydride and water, that 

 it is not susceptible of deoxidation, or amenable, in other words, 

 to the characteristic chemical action of plant-life. On the con- 

 trary, ammonia is the most thoroughly deoxidised, or rather 

 hydrogenetted, compound of nitrogen with which chemists are 

 acquainted. Even nitrogen itself may be looked upon as less de- 

 oxidised than ammonia, being intermediate between ammonia 

 and nitrous acid, thus : 



Nitrogen Molecules 



H N 3 Nitric acid 



H N O a Nitrous acid 



N N Nitrogen 



H 3 N Ammonia 



The nitric and nitrous acids being regarded as oxidised forms 

 of nitrogen, ammonia must be regarded as a deoxidised form, the 

 element quoad its state of oxidation being strictly intermediate 



