n6 SCIENCE PROGRESS. 



observations were made upon Ricinus communis and Linum 

 usitatissimum. According to him both crystalloid and glo- 

 boid originate in the protoplasm and not in the vacuole. 

 He denies that the vacuole has any definite limiting mem- 

 brane or that it has any particular value in the process. 

 Sometimes he was able to observe a little space between the 

 newly-formed grain and the neighbouring protoplasm, but 

 nothing more definite than this. As the globoid, accord- 

 ing to him, is very early to be observed, he goes back to a 

 certain extent to the views of Pfeffer. 



The secretion theory is opposed by Belzung (6), in a 

 paper published in 1891, in which he supports the view of 

 a mere mechanical precipitation much as Pfeffer did. The 

 formation of the grains begins at a somewhat late period, 

 when the cell sap is becoming more or less concentrated. 

 The proteid or albuminoid principles, which will give rise to 

 the grains, are, he says, partly dissolved in the sap by virtue 

 of the alkaline phosphates which are present in solution and 

 partly combined with soda or potash, in the form, therefore, 

 of albuminates of these metals. Very weak solutions of 

 the alkalis are well known to be appropriate solvents of 

 these proteids. Weak acids precipitate the proteids from 

 such combinations in the form of a whitish powder 

 insoluble in water. At this point in the development 

 of the seeds such weak acids, particularly citric acid, 

 are present in the cells and their action causes a gradual 

 precipitation, which proceeds until the aggregation of the 

 precipitate can be seen to take the form of the completed 

 grains. The progressive loss of water as the seed goes on 

 to maturity causes the precipitation to be more abundant, 

 so that the grains grow rapidly. Thus the formation is 

 purely physical. 



He considers his ideas confirmed by the ease with 

 which artificial grains can be produced from solution of the 

 proteids. Werminski obtained them thus from the material 

 of Ricinus, and Bredow from that of Liipimis luteus by a 

 process of dehydration. 



Belzung's description of the way in which the aleurone 

 grains first appear in the cells coincides fairly well with 



