GRAINS OF ALEURONE. 



53 



Fig. 50.— Cells from the &ndo%ptrm oi Rtcinus com- 

 mtifiis (xSoo). A fresh, in thick glycerine, B in 

 dilute glycerine, C wanned in glycerine, D after treat- 

 ment with alcohol and iodine, the aleurone grains are 

 destroyed by sulphuric acid, the albuminoid remaining 

 behind as a net-work. In the aleurone-grains the 

 globoid may be recognised, and in (B, C) the crj'stal- 

 loid. 



The whole albuminous mass (proteine) is now amorphous, and in that case not 

 doubly refractive; or the greater part is developed into the shape of a crystalloid 

 (sect. 7), which, together with the enclosed substances already named, is surrounded 

 by a sparse amorphous envelope, constituting, 

 together with the former, the grain of aleurone. 

 (Fig. 50.) 



The crystalloids are all insoluble in water; 

 neither alcohol nor water extracts anything from 

 them. The grains destitute of crystalloids dis- 

 solve in water entirely (as Pseonia), partially (as 

 Lupinus), or not all (as Cynoglossum). But 

 all dissolve completely in water containing only 

 a trace of potash. With careful treatment there 

 always remains behind a membrane surround- 

 ing the grain, which behaves like coagulated 

 albumen ; but it may be a yet unknown protein- 

 aceous substance. With grains of aleurone con- 

 taining crystalloids, there remains, after careful 

 solution, a similar membrane, but the crystalloid 

 itself also leaves behind a similar one ; this oc- 

 curs also in the solution of globoids in acetic 



or hydrochloric acid, and reminds one of the similar behaviour of true crystals of 

 calcium oxalate. 



The crystalline enclosures of calcium oxalate occur as clusters, clearly recog- 

 nisable crystals, and needles, but are nevertheless not commonly met with. The 

 globoids, on the other hand, are never absent from aleurone-grains ; when they 

 occur together with crystals, it is almost always the case that globoids only are 

 enclosed in one cell, crystals in another (as in Silybum uiarianum, and in all Umbel- 

 liferse that have been examined). There occur how^ever exceptions ; and in Vth's 

 vim/era it is even the case that a globoid forms itself around a crystal or a cluster of 

 crystals. The globoids are soluble in all inorganic acids, and in acetic, oxalic, and 

 tartaric acid, but not in dilute potash. 



The globoids, like the crystals, may occur in an aleurone-grain singly or in 

 numbers ; in the latter case they are small, and the globoid-grains even too 

 minute to be measured, but are then present in enormous numbers in one grain 

 [e.g. Lupinus luteus, L. poljphjllus, Delphinium Requieni, &c.). Large globoids around 

 crystals occur singly, the largest in the grape-vine. Pfeffer found crystals accom- 

 panying crystalloids only in JEthusa Cynapium. The enclosed substances especially 

 are most often absent from very small aleurone-grains. 



In some seeds there is in each cell one aleurone-grain distinguished from the 

 others by its size (Solitar of Hartig), both when crystalloids are present and 

 when they are absent (Elaeis, IMyristica, Vitis, Lupinus luteus) ; and a larger grain 

 of this kind may also be distinguished by its enclosed substances. Thus in Lupinus 

 luteus it possesses a tabular crystal ; the others only small and numerous globoids. 

 In Silybum a cluster of crystals lies in one large grain, in the others a number of 

 needle-shaped crystals. In other cases the enclosed substances are also similar, 



