72 SCIENCE PROGRESS. 



proteids to two parts of water. There is no change in 

 their character in consequence, but their union is a 

 mechanical one, the gliadin forming a gummy or ad- 

 hesive mass, and the glutenin affording a basis or frame- 

 work to which the gliadin adheres. This support enables 

 the gliadin to cause the other parts of the flour to stick 

 together, and thus form the douoh which results when the 

 flour and water are kneaded. 



The authors do not quote any microchemical experi- 

 ments, so that the distribution of the several proteids in the 

 seed has not been ascertained. 



Before leaving the subject of the proteid reserve 

 materials it is interesting to notice that though their com- 

 position may with fair accuracy be ascertained through 

 analysis of them, either in bulk or by microchemical 

 methods, it by no means follows that when once they 

 are deposited in definite reservoirs their composition re- 

 mains unaltered till they are called upon to take part in the 

 nutrition of the plant. Only a few observations on this 

 point are on record, but these lead to the view that even in 

 their most permanent form they are comparatively unstable, 

 and that a certain metabolism is constantly proceeding in 

 the cells in which they lie, in which they are to a greater 

 or less extent involved. The cells at the time of deposition 

 we have seen to be rich in protoplasm, and we have found 

 that it is at least probable that this protoplasm is concerned 

 in the process of their deposition. In the case of carbo- 

 hydrates, such as starch, it has been shown by Brown and 

 Morris (20) while the embryo of the barley is making its 

 way into the parenchyma of the endosperm, and while the 

 latter is thus in a stage during which starch deposition in 

 the cells is proceeding, a form of diastase is present in them 

 with their protoplasm. Whether in the lupin and other 

 seeds any such enzyme is present at a corresponding stage 

 has not been ascertained, but there seems little reason to 

 deny that when the influx of material, which is the source 

 of the aleurone grains, has ceased, the needs of the proto- 

 plasm may require to be supplied by the aleurone itself. 

 Nor is this hypothesis simply ; it can be determined by 



