342 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



reaction peculiarities. Upon such a basis a family might be formed including Brodicea, and 

 certain other genera of the Liliacece that have a recognized very close relationship. 



Similarly, it seems manifest that the family IridacecB, as now constituted, contains 

 a number of genera which should be assigned to other families; as it is, it certainly seems, 

 from the reaction-curves and forms of the starch-grains, to be a very heterogeneous group. 

 If we take the reaction-curve of Iris as being the family type, it will be observed that, 

 as in the case of Liliaceo', the reaction-curves of some of the genera correspond, as for 

 instance Tigridia, while those of others differ so markedly as to suggest misclassification. 

 Thus, for instance, the curves of Morcea and Homeria differ so markedly from the Iris 

 type as to suggest that the genera properly belong to another family. Homeria is stated 

 to be closely allied to Tigridia, but there are certainly well-defined differences in their 

 starches which do not confirm this view. Then, again, Gladiolus, Watsonia, Tritonia, and 

 Antholijza have forms of starch-grains and reaction-curves wliich correspond, but which 

 do not harmonize with the forms and curves of Iris; and Marica and Gelasine differ so 

 from each other, and also from Iris, in the same respects that they could not be identified 

 as members of the same family. In other words, it would seem that the family Iridacew 

 contains a number of genera wliich strictly speaking could with much appropriateness 

 be assigned to other families. These are but few of the many instances suggested bj^ the 

 results of this preliminary study, which indicate that by means of such methods as have 

 been pursued in this research the classification of plants may be revolutionized and placed 

 upon a lasting basis. (See Prefatory Notes in Part II.) 



SUMMARY AND CONCLUSIONS. 



(1) Every starch and every mature starch-grain is a mixture of different forms of the 

 starch-substance. 



(2) Owing to the heterogeneity of starches and the crudities of the methods employed 

 in the differentiation of different starches the results of this investigation are to be regarded 

 as being for the most part of a gross quantitative and cjualitative character. 



(3) The temperatures of gelatinization of starches are as specific in relationship to 

 the chemical composition and constitution of starches as are the melting-points of various 

 isomers in their distinction, and the method employed in this research is approximately 

 exact. 



(4) With each agent the starches exhibit a wide range of reaction-intensity, with a 

 tendency to a close correspondence between varieties of a species, closely related species, and 

 closely related genera, respectively. 



(5) The characters of the modified forms of starch in relation to each genus and each 

 species are specific and constant. 



(6) In pharmacognostics, commerce, and technical pursuits the methods employed 

 in this research must obviously have great value in the identification of vegetable drugs 

 and starches, and in the detection of adulterations and substitutions, and in showing the 

 way of providing starches and other plant products which have such special properties 

 as may be demanded in certain textile industries, etc. 



(7) It is probable that by hybridization and other procedures of the plant-breeder 

 the properties of medicinal substances can be modified by the changes in stereoisomeric 

 forms. 



(8) Stereochemic peculiarities of starches, hemoglobins, and similar complex synthetic 

 metabolites constitute a siriclly scientific basis for the classification of all forms of life. 



Note. At the ends of Chapters II, III and IV (pages 79, 160 and 195, respectively) there will be found sum- 

 maries and conclusions relating to the subject-matter of those chapters. 



