184 LECTURE X. 



apparent. In some cases they contain one or several crystals 

 of calcium oxalate, in most an amorphous mass of mineral 

 matter, the globoid, which consists, according to PfefTer of 

 double phosphate of lime and magnesia. It frequently 

 happens (e.g. Castor-oil plant, Brazil-nut) that a crystal of 

 proteid is also present. In order to distinguish this crystal 

 from mineral crystals, from which it differs in its property of 

 swelling-up, it is termed the crystalloid. 



A B 



FIG. 29 (after Pfeffer). A, an endosperm-cell of Ricinus containing aleurone- 

 grains: B, a single aleurone-grain ; a the globoid, /; the crystalloid. 



I have found that aleurone-grains consist chemically (apart from the 

 globoid or the crystal of calcium oxalate) of proteids of three kinds : (i) of 

 proteids soluble in water, not precipitated from solution by boiling, 

 belonging therefore to the group of peptones; (2) of proteids insoluble in 

 water, but soluble in 10 per cent, or saturated solutions of common salt 

 (NaCl), belonging to the group of globulins j (3) of proteids insoluble in 

 water and in solutions of common salt, but soluble in alkalies ; these are 

 probably derived from the globulins, and are to be regarded as albumi- 

 nates. The crystalloids consist either of a globulin or of an albuminate. 



Pfeffer gives the following account of the development of aleurone- 

 grains. The formation of them begins when the seed has ceased to 

 receive supplies of plastic material from the plant ; for if a seed be 

 removed at the time when the formation' of the aleurone-grains is com- 

 mencing, the formation of them is not interrupted. The inorganic con- 

 tents, the crystals of calcium oxalate or the globoids of double phosphate 

 of lime and magnesia first make their appearance in the protoplasm of 

 the cell, and, in the seeds which contain them, the proteid crystalloids. 

 As the seed in ripening gradually loses water, proteids aggregate at 

 various points in the cells around a single crystal of calcium oxalate or a 

 group of crystals, or around one or more globoids, as the case may be, 

 and around a crystalloid when it is present, and each such aggregation 

 constitutes an aleurone-grain. 



