478 SCIENCE PROGRESS. 



Not only does the cane sugar thus appear to be con- 

 nected immediately with the deposition of starch but it 

 seems also to be the form which is most closely associated 

 with the ultimate nutritive processes. The investigation 

 of the germinating barley grain shows that while the total 

 quantity of it increases during germination, the greatest in- 

 crease is found in the young embryo and not in the endo- 

 sperm. 



Another carbohydrate, more resembling starch than 

 sugar, is the inulin which can be obtained from the roots 

 and tubers of a section of the Composite. Inulin in these 

 parts exists in solution in the sap, but it can readily be 

 made to crystallise out by the application of alcohol. It is 

 considered to stand in the same relation to lsevulose as ordi- 

 nary starch does to maltose, yielding that form of sugar on 

 hydrolysis. The transformation in the plant is effected by 

 a special ferment or enzyme, which exists in the tissue when 

 metabolism is active (40). The course of hydrolysis pro- 

 ceeds much as in the case of starch, an intermediate body 

 being formed which appears to correspond to the dextrin 

 already described. It is interesting to note that starch does 

 not occur in those parts where inulin is present. 



In many plants carbohydrate reserve materials are 

 found to take the form of considerable thickening of 

 the cell walls. That these are really deposited with a 

 view to subsequent utilisation is evident from a study of 

 the seeds of many palms, the endosperms of which consist 

 of little else ; the cavities of the cells being almost oblite- 

 rated, and the small space that is left between the thickened 

 walls containing apparently nothing but a small amount of 

 protoplasm, with which some amorphous proteid matter is 

 mixed. 



That the cell walls yield nutritious matter on germina- 

 tion of the seed can be readily seen by microscopic exa- 

 mination of the endosperm as soon as the young embryo 

 has started its growth. The ce ll walls are then found to 

 be gradually corroded from the line of contact with the 

 embryo, a corrosion which is progressive and continuous so 

 long as the latter remains in contact with the endosperm. 



