52 



from the verb kleben, to stick. " It is the presence of gluten in wheaten 

 flour that imparts to it its viscidity or tenacity, and confers upon it its 

 peculiar excellence for the manufacture of macaroni, vermicelli and 

 similar pastes. The superiority of wheaten over other bread, depends 

 upon the greater tenacity and elasticity of its dough and this is owing to 

 the presence of the " gluten " we are speaking of. The dough during 

 the fermentation and baking is puffed up by the evolved carbonic acid, 

 and so stretched out as to produce the vesicular texture, so much valued 

 in the light loaf." 



This gluten is eminently nutritious, because it consists of albumen- 

 oids, which though insoluble in water, are easily acted on by the digest- 

 ing fluids. It is not, however, a simple chemical compound but con- 

 sists very largely of gluten fibrin. That it is highly nitrogenous may be 

 proved by applying the same test as in the case of the white of egg. 



The percentage composition of gluten fibrin I shall write down 

 alongside of the other albumenoids, so that you may see how very little 

 they vary from one another. 



Percentage Composition. 



Proteids 

 (Vegetable) 



{ Plant Albumen 

 (from wheat) 

 j Legumin (peas) 

 Gluten Fibrin 

 (wheat) 



C. 



53- TO 

 5!-5 



H. 



7.20 

 7.00 



N. 



1 7.60 

 16.80 



S. O &c. 



1 .60 



0.40 



I 



Albumenoids 



Ovalbumen 

 Casein 

 ( Anlmal) ( Fibrin of blood 



5 2 -5 

 53-6 

 53-4 



6.9 



7.0 



I5-25 



i5-7o 

 18.10 



20.50 

 24.30 



54.30 7.20 16.90 1. 00 20.00 



1.93 23.42 

 1. 00 22.60 

 1.20 21.30 



General Molecular Formula 72. 112. 18. 1. 22 



We shall recognize more fully the great importance of these 

 vegetable albumenoids, or proteids as I prefer to call them, when we 

 come to consider later on those of the animal kingdom. Meanwhile 

 what we have again to point out is that these bodies so complicated in 

 their composition and so curious in their properties, are built up in the 

 interior of plants from such inorganic materials as nitrogen, ammonia 

 and nitric acid by the agency of no other apparatus than those tissues 



