ON THE CHEMICAL ASPECTS OF CVANOGENESIS IN PLANTS. 155 



either entirely absent or are present in diminished amount in the leaves — 

 i.e., in the organs in which it is generally assumed the formation of 

 formaldehyde is most actively proceeding. Moreover, several in\'estigators 

 have stated on other grounds that the reduction of nitrates is most active 

 in the leaves. 



While there is no exporimontal evidence of the production of hjxlroxyl- 

 amine when nitric acid reacts with formaldehyde, there can be no 

 objection on theoretical grounds tu Bach's hypothesis ' tliat nitric 

 acid in contact with formaldehyde undergoes reduction in the following 

 step.s : — 



NO.jH— -^NOall >NH/)H 



Nitric Nitrons Hydroxylaminp. 



acid. acid. 



especially since he has obtained indirect evidence of the formation of 

 liydroxylamine by the action of nitric acid on trioxyraethylene. 



The isomeric change of formaldoxime into formamide, the decomposi- 

 tion products of which Bach has detected in the products of the action of 

 ti'ioxymethylene on nitric acid, is probable, since Dunstan and Bossi have 

 .shown that formaldoxime yields ammonia and formic acid when boiled 

 with dilute hydrochloric acid,- and the dehydration of formamide to form 

 prussic acid and water has been recorded liy SchoU,'* whilst its hydrolysis 

 into formic acid and ammonia is a familiar chemical reaction. 



A fui'ther fact in favour of Bach's view may be mentioned. It is well 

 kiiown that Soryhum vulgare is most poisonous when grown in very diy 

 climate.s. This is precisely the condition in which natural dehydration 

 would oc'cui, and if Bach's view be adopted it might lie expected that in 

 seasons of drought an unusually large proportion of the formamide in 

 .sorghum would be dehydrated and an abnormal production of prussic acid 

 take place. Similar observations have been made witli regai'd to cassava, 

 which is peculiarly virulent when grown in the dry districts of South 

 America, but, according to Wiley, yields much less prus.?ic acid when 

 grown under moist climatic conditions, as in the West Indies or the 

 United States. It is also worth mentioning in this connection that 

 Leather has ol)tained a much larger proportion of prussic acid from flax 

 (linseed) plants grown in India than has been recorded by European 

 workers who have investigated flax plants grown in colder and moister 

 climates. 



It will be observed that Bach oflfers no suggestion that prussic acid 

 takes any further part in the metabolic process, and he appareiitly regards 

 it as an accidental product of little importance, 



Gautier's theory^ differs fundamentally from these of Mpyer 'iiicl 

 Schulze and Bach, This author supposes th.at the free nitric acid of 

 cell sap reacts with formaldehyde, forming free prussic acid, carbon 

 dioxide, and water, It js then suggested that the prussic acid formed, 

 condenses with formaldehyde, forming a chain such as 



I ^ II 



:CNHCH0HCH0HCNHCH0HCHOHNHCC.=NH, 



I I 



in which it is supposed that the=C*NH groups undergo hydrolysis and 



' Monitfur Scientifique, 18i)7, iv. 11, I. 



- Journ. Chem. Soc, 1898, 73, 3.'>4. « lier., 1891, 573. 



♦ BuU. Soc. Chim. 1872,42, 141, and Lecons de Cltimie Bid, Vms, Masson et 

 Cie., 1897. 



