CHAPTER I. 



INTRODUCTION. 



OBJECTS OF THE RESEARCH. 

 This research was undertaken with three primary objects in view: First, to deter- 

 mine if the hypothesis underlying the hemoglobin investigation would be supported by 

 the stereochemic peculiarities of other complex synthetic metabolites; second, to add 

 materially to our knowledge of one of the most important substances in the life-history 

 of both plant and animal kingdoms; and third, to throw open fields of investigation which 

 offer extraordinary promise, particularly in adding to our knowledge of the all-important 

 properties of protoplasm. In the previous research it was clearly demonstrated that 

 hemoglobin exists in isomeric forms which are specifically modified in relation to genera 

 and species, and differing to so marked a degree that by means of such variations 

 species and genera could be recognized. Starch was selected as the second subject of 

 investigation, primarily, as stated in the Preface, because of its being so different from 

 hemoglobin in its relations to the parent substance, in its chemical composition and con- 

 stitution, and in its role in life's processes; and, moreover, because of its especial value 

 in such an inquiry owing to its extremely large and complex molecule and high carbon 

 content. 



THE vSTARCH-GRAIN. 



Starch exists m silu both as " soluble starch " and starch-grains or granules, almost 

 solely as the latter. In the soluble form it has been found in the cell-sap of the epidermal 

 cells of Saponaria officinalis and Arum itnlicum, and in a number of other plants. Starch- 

 grains have long been recognized as occurring in a great variety of forms. Fritzsche, in 

 1834, recorded that not only are the starches from different plants not alike, but also that 

 often the form was so characteristic as to determine the plant, or at least indicate the 

 genus and family to which the plant belonged. This observation was confirmed by Schlei- 

 den and other investigators. Niigeli, the most noted authority on starches, stated in 

 his elaborate memoir published in 1858, after examining over 1,200 different kinds of 

 starches, that all genera of a natural order frequently contain starch-grains which are 

 closely related, and that sometimes a distinction is shown between genera, and then usually 

 also between species, so that plants may be classified into natural groups according to the 

 structure of their starches. Nageli's records also show that starches of like gross histological 

 characters may be found in entirely different genera, families, and orders; and, moreover, 

 that even in the same family the starches of different genera may differ more or less markedly, 

 or, indeed, be entirely unlike. Even though such differences in form exist, it is by no means 

 necessarily implied that such variations are an expression of different kinds of starch, because 

 they may be entirely accounted for upon the basis of attendant conditions. 



The starch-grain, excepting perhaps at its earliest stage of formation, is a sphero- 

 crystal, and is produced by specialized protoplasmic bodies which are designated plastids. 

 The forms of the starch-grains are dependent in j^art upon the molecular peculiarities of 

 the plastids, the form of the plastid, and the position of the plastid in relation to the sur- 

 face of the grain; and in part upon a number of incidental conditions, such as variations 

 in the composition of the cell-sap, the presence of foreign bodies in the form of crystals 

 of protein or other solid masses, mutual pressure of starch-grains, etc. Were the plastid 



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