176 O'Brien. — The Proteids of Wheat. 
corresponds to the albumin both of blood-serum and of white 
of egg. It is in fact suggested that fibrin, existing in the 
plant in a soluble state, may be the mother- substance which 
gives rise to albumin as a secondary product. Though glutine 
and myxon are described as isomeric, yet the former is placed 
with the vitelline of egg-yolk outside the group of true 
proteids ; whilst myxon is named caseine. So closely how- 
ever is it also allied to albumin that the question arises, 5 Is it 
indeed true casein, or a modification of albumin which has 
some of the properties of casein?’ There is here an important 
difference from Liebig, according to whom casein is represented 
in the vegetable kingdom by legumin, and does not occur in 
wheat. We may notice that Dumas considers legumin as 
a mixture of casein and albumin with a third substance richer 
in nitrogen ; whilst Ritthausen later classifies legumin as 
a vegetable casein, with zymom (gluten-casein), and not with 
any part of the alcohol-soluble proteid of gluten (glian). 
Thus more than fifty years ago some of the problems of 
modern vegetable physiology were at least clearly stated : and 
though perhaps the outlines of the classification of proteids 
may be for the present considered settled, yet the position of 
the characteristic proteids of wheat is no better defined than 
it was half a century ago, and the questions then raised as to 
the possible transformation of one form into another are still 
without satisfactory answer. 
No further addition seems to have been made to the know- 
ledge of gluten till about i860, when we come to the work of 
Von Bibra, Giinsberg, and Ritthausen. Although in the 
interval an important step in the investigation of the proteids 
of the blood had been made by Denis, the advance in animal 
physiology did not affect the methods of vegetable physiology 
till nearly 1870. 
Von Bibra 18 , writing in i860, seems (as quoted by Ritt- 
hausen) to have kept to the subdivisions of Berzelius and 
Dumas, viz., fibrin [zymom], Pflanzenleim [glutin], casein 
[myxon]. 
Giinsberg 19 (1862) comments severely on the confusion of 
