THE RESERVE MATERIALS OF PLANTS. 479 



It has been observed moreover in the germination of the 

 seeds of several grasses, where a special provision for its 

 utilisation has been found to exist in the form of a special 

 enzyme. The usual store of cellulose need not necessarily 

 be a thickening of the cell wall, for the original wall itself 

 is used up as the embryo grows. 



When cell walls are thickened for the use of the 

 embryo, as in the cases mentioned, the thickening is often 

 considerably modified in its chemical composition, although 

 retaining a close relationship to cellulose. Reiss (58) and 

 E. Schulze (59) have described two particular substances 

 of this character, Reiss naming the first reserve-cellulose, 

 and Schulze giving the name " paragalactan compounds" 

 to the second. The latter have also been called heini- 

 celluloses ; they are converted into glucose and dissolved 

 by hot dilute mineral acids, which do not affect cellulose 

 proper. 



Reiss's body exists in the endosperm of Phoenix dacty- 

 lifera, Phytelephas, and other palms. On hydrolysing it 

 with sulphuric acid there is first formed a compound corres- 

 ponding to dextrin, but kevo-rotatory. This is followed by 

 a sugar, which is dextro-rotatory, reduces Fehling's fluid, 

 and is capable of fermentation. To this sugar the name 

 seminose has been given ; it forms with phenylhydrazin 

 acetate a compound which is crystalline. Reserve cellulose 

 cannot be distinguished by microchemical reactions from 

 ordinary cellulose. 



Schulze has investigated Reiss's body and includes it 

 under the name mannose among his hemicelluloses. 



Paragalactan occurs in the thickened wall of the cells 

 of the embryo in certain Leguminosse. It yields on 

 oxidation mucic acid ; on heating with dilute sulphuric acid, 

 galactose, and a pentaglucose. When heated with phloro- 

 glucin and hydrochloric acid it gives a red colour, but not 

 in the cold as lignin does. It is hydrolysed into- sugar by 

 1 per cent, hydrochloric or sulphuric acid, and is not 

 coloured blue by chloriodide of zinc. 



The accumulations of mucilage in definite areas or 

 layers in certain seeds seem to have the same purpose as 



