PREFATORY NOTES. 



The laboratory records of the properties of 

 starches that compose this chapter were prepared by 

 two of the author's assistants, Dr. Elizabeth E. Clark 

 and Miss Martha Bunting (see page 22). The work 

 was carried on in accordance with the plans and 

 methods laid down by the writer, and the data here 

 presented are given substantially verbatim et liter- 

 atim, the only material alterations made having been 

 in the elimination of a large volume of seemingly 

 unessential matter and in occasional changes to elim- 

 inate ambiguity. These records fall into two natural 

 groups quantitative and qualitative. The former, 

 as previously stated, and as is evident by the context, 

 are admirably adapted to comparative summarizing, 

 tabulation, and charting ; while the latter can be satis- 

 factorily utilized in this way, within reasonable limits 

 of space, to only a very limited degree. 



It is a fact, of fundamental importance that the 

 quantitative and qualitative records pertaining to the 

 reactions of any given starch with any given reagent 

 may bear no relationship, as, for instance, when the 

 time-reactions are the same but the qualitative reac- 

 tions differ, and vice versa. The quantitative reactions 

 of a given starch with different reagents vary within 

 narrow to very wide limits, depending upon the kind 

 of starch and the kinds of reagents ; and the quali- 

 tative reactions vary not only quite as markedly, but 

 also exhibit at times peculiarities that are not only 

 not indicated by the quantitative reactions, but 

 which are of great importance in demonstrating 

 singularities in the physico-chemical constitution of 

 the starch. Any such peculiarity may be one that is 

 common to a genus, species, or variety, or that is in- 

 dividual to a parent or its offspring. Moreover, in 

 every kind of starch, whatsoever the plant source, 

 there may be found several histologic types of grains 

 which vary in number and kind in different starches, 

 which types may be distinctive of a genus, species, 

 variety, or individual. Furthermore, as pointed out 

 in the preceding memoir (page 302), the starch of 

 any given plant, and even that composing an indi- 

 vidual grain, is not a unit-substance, so that the 



different types of grains, as well as the individual 

 grains, are each composed of a number of modifi- 

 cations of a given form of starch. As a consequence, 

 the several types of grains, the primary and secondary 

 and tertiary lamellae, and the different lamellae of a 

 simple grain, may each exhibit more or less distinctive 

 differences in either or both quantitative and quali- 

 tative reactions, and these are apt to be notably con- 

 spicuous in the latter. 



The quantitative reactions, as shown, offer con- 

 vincing evidence of the value of the physico-chemical 

 method in the demonstration of the characteristics of 

 starches in relation to genera, species, and varieties, 

 and to parents and offspring; and while the qxiali- 

 tative reactions have received scarcely more than the 

 most casual references, it will be found that they are 

 not less striking and cogent, and in certain respects 

 even more suggestive, valuable and remarkable. 

 Attention is therefore now directed particularly to 

 the latter. Inasmuch as the general reader will likely 

 glance with some degree of hopelessness over the con- 

 siderable mass of data that represent the qualitative 

 reactions, it is suggested that a critical perusal of the 

 records that pertain to a single set of parents and 

 progeny, such as those of the Amaryllis-brunsvigiar 

 Irunsdonnce set, will prove quite an easy and short 

 road to obtaining a good insight into the similarities, 

 dissimilarities, and individualities of each parent and 

 each hybrid, and of the variable and wholly unpre- 

 dictable ways in which characters and character- 

 phases are or are not transmitted, and new characters 

 appear in the offspring. Obviously, such reading 

 should be supplemented by a study of the quantitative 

 records, and this, in turn, by comparisons of all of the 

 data of different sets of parents and hybrids of the 

 same genus and of different genera, etc. One will not 

 find at present in any other line of investigation so 

 fertile a field for speculation and theory of the mech- 

 anisms of heredity in general, and, by no means of the 

 least interest, those concerned in the genesis of new 

 forms. 



