BUILDING OF LIVING MATTER 115 



the nature of the organic acid had to be 

 mentioned, and the formula of one with six 

 carbon atoms was set down. It was repres- 

 ented by a chain of carbon atoms, united to 

 each other by two affinity centres, and with 

 the other centres satisfied by hydrogen 

 atoms, save in the case of one of the terminal 

 carbon atoms, where, instead, was found the 

 acidic group in which one hydroxyl group 

 (HO) and one oxygen atom (O) held the 

 available affinities, so giving the formula :— 



H H H H H HO 

 I I I I I I 

 H-C-C-C-C-C-C=0 



I I I I I 

 H H H H H 



This is an acid, but if now the substance, 

 ammonia, represented by the formula, 

 H-N-H, 



I be taken and supposed to have lost 



H 

 one of its hydrogens, it then acts as a monad 



-N-H, 

 group 1 which can replace a hydrogen 



H 

 atom in the above formula. This can be 

 done experimentally by means which need 



