372 



NOTES AND CONCLUSIONS. 



gation that the temperatures of gelatinization of starches 

 from different sources vary within a range of over 40 

 C. ; and that the figures for the starches of different 

 members of a genus usually tend to keep within limits 

 of about 5, the closer the plant sources the closer the 

 temperatures. Moreover, qualitative differences similar 

 to those elicited by the various chemical reagents have 

 been observed, and they are worthy of detailed study. 

 These it seems will be found to differ not only in dif- 

 ferent starches, but also to differ from the reactions 

 elicited by the chemical reagents and to differ as much 

 from them as they do from each other. These qualitative 

 reactions have been found, as a whole, to have such 

 values as to recommend them for extensive use. In the 

 present research these reactions with heat and chemical 

 reagents have yielded records that are of especial interest 

 in the differentiation of the starches of the hybrid- and 

 parent-stocks, and they have not only shown peculiari- 

 ties of the hybrid that are the same as those of one or 

 the other parent or both parents, but also individualities 

 not observed in either parent and corresponding to what 

 was found in the records of the histologic and other 

 characters and character-phases. The extraordinary 

 plasticity and complexity of the starch molecules and its 

 character and character-phase potentialities offer endless 

 opportunities in this form of investigation. 



The quantitative data appeal more to both experi- 

 menter and reader because they lend themselves so 

 admirably to reduction to tables and charts. The possi- 

 bilities for additions to our knowledge of this kind are 

 unlimited. As previously indicated, the number of 

 starches available for such investigations is enormous 

 and the number of the reagents can be considerably 

 amplified. Moreover, there can often be used, to much 

 advantage, several concentrations of the same reagent 

 and also combinations of certain reagents. 



These various reagents differ markedly in their 

 values in the quantitative and qualitative reactions, 

 respectively, and some are better for the former than the 

 latter and vice versa; moreover, a reagent that may be 

 particularly good for qualitative reactions with one form 

 of starch may be inferior for another form, and so on. 

 Recognition of these points will be of great advantage 

 in subsequent investigations. 



STARCH SUBSTANCES AS NON-UNIT SUBSTANCES. 



Starch from any given plant is a heterogeneous col- 

 lection of grains which vary in microscopical and 

 molecular properties ; even the individual grains, except 

 perhaps the very small embryonic, spherical, and seem- 

 ingly amorphous forms, are likewise of non-uniform 

 composition. The differences in the behavior of the 

 inner and outer parts or (according to general ideas) 

 of the so-called amylose and cellulose can be demon- 

 strated with the greatest ease and in ways to show that 

 these parts represent different forms of starch-substance. 

 As already repeatedly pointed out, the individualities of 

 these two parts are markedly shown in their different 

 behavior towards various reagents. As a rule, the outer 

 part is the more resistive, but toward some reagents it is 

 the less resistive. In relation to moist heat, when the 

 grains are boiled in water the outer part- is always the 

 last to disappear, sometimes resisting boiling for many 

 minutes, appearing in suspension in the form of empty 



capsules from which the less resistive inner starch has 

 escaped in semi-liquid form and passed into a pseudo 

 solution. 



The different lamellae of the mature starch-grain are 

 of less and less density from without inward. These 

 peculiar variations are, it seems clear, not owing to an 

 increase in the density of each additional lamella as it 

 is deposited, but to a gradual transition of the molecular 

 states of the inner or older lamella? to a less dense con- 

 dition. Such a change is explicable in the light of the 

 ready transmutability of one stereoisomeric form into 

 another owing to slight differences in attendant con- 

 ditions. (See preceding memoir Publication No. 173, 

 page 9.) The mere separation of the starch from direct 

 contact with the plastid or the cell-sap by the later-de- 

 posited starch, age, and other incidental conditions, are 

 of themselves doubtless sufficient to satisfactorily account 

 for this transmutation. Likewise, differences in other 

 parts, such as in primary and secondary lamellse, pro- 

 tuberances, etc., in relation to other parts of the grains, 

 may be explained in the same way. 



EACH STARCH PROPERTY AN INDEPENDENT PHYSICO- 

 CHEMICAL UNIT-CHARACTER. 



Each starch property, whether it be manifested in 

 peculiarities in size, form, hilum, lamellation, or fissura- 

 tion, or in reactions to light, or in color reactions with 

 iodine or anilines, or in gelatinization reactions with 

 heat or chemical reagents, is an expression of an inde- 

 pendent physico-chemical unit-character that is an index 

 of specific peculiarities of intramolecular configuration, 

 the sum of which is in turn an index which expresses 

 specific peculiarities of the constitution of the proto- 

 plasm that synthetized the starch molecule. The unit- 

 character represented by the form of the starch grain is 

 independent of that size ; that of lamellation independent 

 of that of fissuration, etc. This is evident in the fact 

 that in different starches variations in one may not be 

 associated with variation in another, and that when 

 variations in different properties are coincidently ob- 

 served they may be of like or unlike character. Gela- 

 tinizability is one of the most conspicuous properties of 

 starch and it represents a primary physico-chemical 

 unit-character, which character may be studied in as 

 many quantitative and qualitative phases as there are 

 kinds of starches and kinds of gelatinizing reagents, the 

 phenomena of gelatinization by heat being distinguish- 

 able from those by a given chemical reagent, and those 

 by one reagent from those by another, and those of one 

 starch by a given reagent from those of another starch. 

 The gelatinization of the starch grain is not only a very 

 definite chemical process but one that must vary in 

 character in accordance with the reagent entering into 

 the reaction. It follows, as a corollary, that the prop- 

 erty of gelatinizability of any specimen of starch may be 

 expressed in as many independent physico-chemical unit- 

 character-phases as there are reagents to elicit them. 



INDIVIDUALITY OR SPECIFICITY OF EACH AGENT AND 

 KEAGENT. 



The methods employed in the research, all micro- 

 scopic, have, as stated, included inquiries into histo- 

 logic characters ; polariscopic, iodine and aniline reac- 

 tions ; temperatures of gelatinization ; and quantitative 



