r^ MORPHOLOGY OF THE CELL. 



as is always the case with the globoids, which are especkilly larger in the large 

 grain. 



The crystalloids are tolerably widely distributed, although the greater number 

 of seeds are destitute of them. They are not, however, characteristic of families, 

 but may be present or absent in members of the same family ; thus among palms, 

 Sabal Adansonii is without, Elaeis guineensis provided with crystalloids ; in the same 

 manner all Umbelliferse which have been investigated are deficient, with the excep- 

 tion of JEthusa Cynapiuni, &c. In other cases ail seeds of the same family appear 

 to contain crystalloids, as in the Euphorbiacese, among which in particular Ricinus 

 offered the first example of fine crystalloids in the grains of aleurone. 



The matrix which surrounds the grains of aleurone in oily seeds is, as has been 

 mentioned, always a mixture of oily matter and albuminoids, but the latter may 

 be in very small quantities. Thus even in Ricinus and the brazil-nut, where 

 the matrix appears to consist entirely of oily matter, the albuminous constituent 

 is yet quite discernible, as is shown in Fig. 50, D; Pfeffer succeeded most readily 

 by extracting with an alcoholic solution of calomel, and then colouring with 

 aniline-blue dissolved in water. The matrix may be considered as the proto- 

 plasmic mass of the cell, in which the water is replaced on drying by oil. 

 But in addition it contains in the whole mass, not only insoluble albuminoids, but 

 other substances also which are soluble in water containing potash in solution. 

 This composition of the matrix, together with the solubility of the amorphous mass 

 of the aleurone-grains in water, are the cause of the complete loss of form which 

 the cell-contents of oily seeds immediately undergo in water (sections under the 

 microscope). In order to recognise their structure it is necessary to place fresh 

 sections in thick glycerine, or in alcoholic solution of calomel, in concentrated 

 sulphuric acid, or in oil. 



The oily matter may besides separate out of the matrix in crystals, as Pfeffer 

 has observed in the brazil-nut, Elaeis guineensis^ and the nutmeg. 



To the above may be added from Pfeffer's communication some explanations con- 

 cerning the more difficult points. 



(a) The Mass of the grains of aleurone always consists to by far the greater extent of 

 proteinaceous substances, with which only very small quantities of other vegetable sub- 

 stances are usually or always mixed; these, nevertheless, are difficult of detection. 

 This conclusion rests essentially on the following grounds : — all aleurone-grains are 

 absolutely insoluble in alcohol, ether, benzol, and chloroform (that I formerly con- 

 sidered them soluble in ether, was the result, as Pfeffer showed, of the ether con- 

 taining a small quantity of water). All these reagents would dissolve oil (alcohol 

 dissolves also glucose), if it were present, and would consequently also alter the 

 appearance of the grain. There are grains insoluble in water {e.g. Cynoglossum officinale')', 

 those soluble in water ^ pass over, on digestion with absolute alcohol in which corrosive 

 sublimate has been dissolved, into an insoluble mercury-compound, out of which water 

 dissolves nothing worth notice. Gum, pectinaceous substances, cane-sugar, and dextrine, 

 do not, under this treatment, yield an insoluble compound. Of all widely distributed 

 vegetable substances, only a proteinaceous substance can be mentioned which behaves 

 in this manner towards corrosive sublimate. This may be recognised by reactions, of 





* On the causes of the solubility in water Pfeffer's exhaustive treatise which is immediately to 

 ippear must be referred to. 



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