THE RESERVE MATERIALS OF PLANTS. 71 



is precipitated on neutralisation of the solution without any 

 alteration ; a point indicating a possible relation to the 

 derived albumins of digestion, from which, however, its 

 relation to alcohol separates it. When it is warmed with 

 sulphuric acid of 50 per cent, concentration it slowly 

 assumes a violet colour, which is increased in intensity by 

 boiling. Concentrated hydrochloric acid causes the same 

 coloration. 



Though similar to zein in its behaviour with alcohol, 

 the authors consider it not to be identical with the latter. 



The remaining proteid of the seeds has been called by 

 the discoverers gluieniii. It is only slightly soluble in 

 warm alcohol or in warm water, but can be prepared from 

 the flour by treating it with dilute acids or alkalies. If it be 

 precipitated from the solvent, dehydrated with absolute 

 alcohol, and dried over strong sulphuric acid, it dissolves 

 slowly again in the same reagents, but leaves a little coagu- 

 lated residue. Before the dehydration the precipitate is 

 very readily soluble in either weak potash or dilute hydro- 

 chloric acid. 



It differs from gliadin in its reaction with 50 per cent, 

 sulphuric acid, turning brown instead of violet; it takes on the 

 latter colour, however, with concentrated hydrochloric acid. 



From the general similarity of its reactions to those of 

 gliadin it seems possible that it may be a result of some 

 decomposition of the latter. The discoverers, however, 

 think it is a wholly distinct body, as it cannot be prepared 

 from rye flour, though the latter contains a good deal of 

 gliadin. Glutenin is almost as plentiful in wheat as gliadin, 

 nearly 4 per cent, of the flour being composed of it. 



Both gliadin and glutenin being capable of preparation 

 from gluten, as well as from flour, these investigations 

 throw a good deal of light on the constitution of the latter. 

 There appears to be no transformation of its constituents 

 as in the process of the formation of fibrin, nor is any 

 ferment necessary for its production. To form gluten the 

 authors put forward the view that the gliadin and glutenin, 

 both of which exist separately in the wheat endosperm, 

 combine with water in the proportion of one part of the 



