Attention has been drawn to our ignorance concerning the nature of the proteins of green forage plants and the gap in the science of nutrition which arises thereby in trying to apply to forage plants results obtained from proteins of concentrated foods.

Methods of extraction of proteins from green tissue are outlined and applied to the study of the proteins of some common representative leguminous plants.

The proteins so isolated have been analysed and characterised. Proteins thus prepared were found to resemble each other closely with respect to distribution of nitrogen into three groups.

Representative samples of proteins were found to differ appreciably in their content of the different diamino acids as determined by the van Slyke method, showing variation to occur in the composition of protoplasmic proteins within a natural order, which confirms the observations of other workers on seed proteins within a natural order.

The occurrence of large amounts of mineral matter in the extracts from lucerne, vetch and sainfoin, but not in those of the two clovers, together with the difficulty of obtaining pure samples of proteins from the clovers, points to the slightly less nutritive properties of the latter owing to the lesser availabilities in them of both the protein and ash.

The nitrogen distribution in the protein-free extracts shows the amide nitrogen to be constant but ammonia nitrogen to be variable.