162 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



rearrangement of the atoms of the molecules so that in either case the product is of a depol- 

 ymeric form. The conversion of dextrin into maltose, and of maltose into glucose, we are 

 certainly justified in regarding as being due to hydrolysis, by which molecules of water are 

 taken up and constitute not only a part of the process but also a part of the product. 



Starch is classed among the most typical of the so-called colloids, yet, like many or 

 probably all of the so-called colloids, it may exist in crystalline form; likewise are many 

 simple inorganic substances colloidal, as for instance silicic acid, platinum, gold, sih'er, 

 ferric hydroxide, arsenious sulphide, aluminum hydroxide, etc. In fact, it seems probable 

 from the advances of physical chemistry that any substance, according to conditions, may 

 exist in either a colloidal or crystalloidal state. Hemoglobin in the erythrocyte exists in a 

 colloidal state, yet when freed it is usually easily obtained in a crystalline state ; egg albumin 

 and serum albumin are imder normal conditions typical colloids, yet they may be crystal- 

 lized. Boiled starch is a typical colloid, but when demineralized and rendered by high 

 moist temperature into a true solution it is thus transformed into a crystalloidal state or 

 phase. The transition of colloidal into non-colloidal forms of starch and of dextrin into 

 maltose or some other form or forms of sugar are instances of the readiness with which an 

 alteration from one state to another can be brought about in the transition of intimately 

 related substances, one into the other. It seems therefore, as is being generally recognized, 

 that we are not dealing with colloidal or crystalloidal substances, but with corresponding 

 states, phases, conditions, or forms. Hence, the transition of a typical colloidal state of 

 starch into a crystalloidal state, and the reversal, are phenomena that were to be expected. 

 In fact, the line of demarcation between these two classes of substances, or better, between 

 these two states, is by no means so definitely defined as is generally believed, for not only 

 are there substances which may be so arranged that every transitional stage may be filled 

 in between the most typical colloid and the most typical crystalloid, but also it is found that 

 the transition from one state to the other occurs with such apparent ease that the two 

 states can not be so far separated as it would seem upon superficial investigation. This 

 facility of transition is well illustrated in the ^'arious steps in the saccharification of starch : 

 The starch-grain has a crystalline structure as well defined as the structure of sjjhero- 

 crystals of many typical inorganic crystalloids; by the adsorption of water the crystallized 

 starch is converted into a typical colloid that forms a typical /jscMf/o-solution ; by deminer- 

 alization of the pseudo-solution and subjection to high moist heat, a true solution is formed, 

 and hence the colloidal starch is transformed into a crystalloidal form; by the action of 

 diastatic enzymes the starch in this crystalloidal state is converted into erytlu-odextrin, 

 another colloidal substance normally existing in a colloidal state, but having certain col- 

 loidal properties which distinguish it from starch; by further action of the enzyme this 

 colloid erythrodextrin is converted into another colloid in the form of achroodextrin with 

 the assumption by this substance of a further modification of properties ; from this dextrin 

 normally existing in a colloidal state there is formed maltose, a typical crystalloid; and 

 from maltose there may be derived glucose, which as we are accustomed to see it is a crys- 

 talloid, yet (like iron, etc.) it may exist in colloidal form in combination with certain pro- 

 teins. It goes without saying that, inasmuch as the processes of life are inseparably 

 associated with protoplasm, and hence with the colloidal state of matter, that the interrela- 

 tions of colloidal and crystalloidal states, together with the surprising readiness with which 

 transitions from one state to another can be brought about, are phenomena of the greatest 

 fundamental importance, and that every advance along these lines must bring us closer 

 to the mechanics of protoplasm. Of no less fundamental importance are the transient 

 and permanent effects of changes of external conditions on the constitution of starch, 

 gelatin, fibrin, and such substances when in a colloidal state (page 96), for it seems that 

 in these effects we have a primitive expression of the influence of changes in internal and 

 external conditions upon the constitution of protoplasm, and hence upon its reactions; 



