52 



MORPHOLOGY OF THE CELL, 



to Starch-grains in their appearance, and surrounded by a more or less homo- 

 geneous matrix, which, as closer investigation shows, consists, according to the 

 oiliness of the seed, of more or less oil combined with proteids. The grains 

 themselves, on the other hand, consist, independently of certain enclosed matters, 

 of proteids. 



In the aleurone-grains the proteid itself must be distinguished from the 

 enclosed substances. The latter are either crystals of calcium oxalate, or non- 

 crystalline, roundish, or clustered granules, known as Globoids. These are a double 

 calcium and magnesium phosphate, in which the latter base is greatly in excess. 



Fig. 46. — Cells shown in a very thin section througli a 

 cotyledon in a ripe seed of Pisutn sativutn; the large 

 concentrically stratified grains st are starch-grains (cut 

 through) ; the small granules a are aleurone, consisting 

 principally of legumin with a little oily matter; ?the inter- 

 cellular spaces. 



Fig. 47.— Cells from the cotyledon in a ripe seed oi Lupinus varius ; A in an alcoholic solution of iodine ; B after destruction 

 of the aleurone-grains by sulphuric acid ; z the cell-wall ; p the protoplasmic matrix, containing but little oily matter ; y the 

 aleurone-grains ; a drops of oil expelled from the matrix by the action of the sulphuric acid ; m empty spaces from which the 

 aleurone-grains have been dissolved (x 800). 



The whole proteid is sometimes amorphous, and in that case is not doubly 

 refractive; or the greater part, with the enclosed substances already named, is 

 developed into a crystalloid (Sect. 7), and this, surrounded by a thin amorphous 

 envelope, constitutes the aleurone-grain. (Fig. 48.) 



The proteids are all insoluble in water; neither alcohol nor water extracts 

 anything from them. The grains which contain no crystalloids dissolve in water 

 entirely {Pceonia)^ partially [Lupinus), or not at all [Cynoglossum). But all dissolve 

 completely in water containing only a trace of potash. With careful treatment there 

 always remains behind a membrane surrounding the grain, which behaves like 



