RESERVE MATERIALS OF PLANTS. in 



their transformation into the forms found in the circulating 

 fluid, under the influence of various ferments and other agents 

 and under the control of the protoplasm found with the stores 

 in the reservoirs. 



In dealing with the materials which constitute the re- 

 serves of plant food we must therefore discriminate between 

 these two descriptions of substances. Generally we find 

 a distinction possible in the degree of solubility which at- 

 taches to them. The carbohydrates of the reservoirs are 

 mainly starch or inulin ; those of the circulating sap some 

 form of sugar, or vegetable acids derived therefrom. The 

 nitrogenous bodies of the seed are usually either definite 

 grains or collections of amorphous proteids ; those of the 

 sap are mainly diffusible proteids or amide bodies largely 

 derived from them. 



In setting out to discuss the various forms of reserve 

 materials, their modes of disposition and their fate, this must 

 be borne in mind and the relations of the two classes 

 recognised. 



The kinds of material found in plants which belong to 

 one or other of these categories are extremely numerous 

 and varied. Their places of temporary deposit are very 

 widespread, some charged with great abundance of nutritive 

 substance and evidently set apart for a prolonged resting 

 period ; others containing a little only and this intended for 

 only a short stay in its place of deposition. In seeds, 

 tubers, bulbs, corms, fleshy roots and stems we recognise an 

 almost permanent deposit ; in medullary rays and cells of 

 vascular tissue, in sieve tubes and laticiferous vessels, we find 

 material laid down for only brief periods, ready for an al- 

 most immediate demand on the part of the living cells. In 

 these cases we find each to have its most appropriate form, 

 the temporary stores being as a rule of a more easily trans- 

 formed character than the more permanent ones. 



The nitrogenous reserve materials, in whichever of the 

 two descriptions of reservoir we find them, are largely met 

 with in the shape of some form or other of proteid matter. 

 Till within recent years much obscurity existed as to vege- 

 table proteids, many bodies with very curious reactions being 



