354 The Physiology of Plants BOOK in 



Bach suggested a first reduction of the free nitric acid 

 liberated as Emmerling supposed, in the same way as it 

 is reduced by sulphurous and hydrosulphurous acids, the 

 reducing agent being formaldehyde. Such a reduction 

 would yield in succession nitrous and hyponitrous acids 

 and finally the group NH, which would unite with water 

 to form hydroxylamine. The latter reacting with formalde- 

 hyde would give besides water formaldoxine, which is 

 readily convertible into formamide ; from this again, by 

 dehydration, hydrocyanic acid can easily arise. 



His theory was supported by the observation he made 

 that when formaldehyde reacts with nitric acid, form- 

 aldoxine occurs among the products. Bach thought he 

 detected formamide also. 



Gautier, in 1892, suggested that hydrocyanic acid might 

 form the nucleus of protein, various radicals becoming 

 attached to it. He showed that it polymerizes easily, and 

 in that way lends itself to the production of new complexes. 

 Kossel discovered one of these, adenine (C 5 H 5 N 5 ), in different 

 plants, so that Bach's hypothesis may very well be regarded 

 as provisionally a working one. It received some sup- 

 port not only from his own researches, but from those of 

 Treub in 1895, in which the latter showed that in Pangium 

 edule cyanides occur at or near the seats of protein con- 

 struction. From their distribution and manner of appear- 

 ance Treub concluded that they formed the first product 

 of the appropriation of the nitrogen by the plant. Treub's 

 discovery of the existence of hydrocyanic acid in plants 

 was confirmed by other writers and by his own later 

 researches. So far, however, it does not appear altogether 

 clear that it is a product of the synthetic processes ; some 

 observers hold it to be rather derived from protein by 

 decomposition. 



Lutz endeavoured to test Bach's hypothesis by searching 

 for hydroxylamine in various species of Phanerogams, Algae, 



