32 



HISTOLOGIC PROPERTIES AND REACTIONS. 



The marked variabilities that are exhibited by the 

 reaction-intensities of the starches of the hybrids in 

 relation to those of the parents, coupled with the im- 

 portance that is almost invariably attached to inter- 

 mediateness as a criterion of hybridism, led to the 

 introduction of Section 5, which summarizes the reaction- 

 intensities of the starches of the hybrid as regards 

 sameness, intermediateness, excess, and deficit of reac- 

 tion-values in relation to one or the other parent or both 

 parents. The statements herein are based upon the tables 

 A 1 to A 26, and the Charts D 1 to D 670 in Chapter IV, 

 page 210. The quantitative relations of the reactions 

 of the hybrid to those of the parents could not in some 

 instances be satisfactorily determined, because usually of 

 too rapid or too slow reactions, variant courses of reac- 

 tion, or differences that are so small as to fall within 

 the limits of error of experiment; and differences may 

 be seen in the tables that can not be or are not satisfac- 

 torily presented in the charts, especially such as may be 

 recorded during the first 5 minutes of the experiments. 

 When the reactions are very rapid, any differentiation 

 must be determined very early, and unless the records 

 differ markedly the hybrid is credited with sameness in 

 relation to one or the other or both parents, as the case 

 may be. Sometimes there may be no differences early in 

 the experiments, but marked differences occur later, in 

 which case the values are determined late, and so on. 

 Occasionally one or more of the curves will take on a 

 variant course, so that the hybrid relationships to one 

 or the other parent or both parents may be different at 

 different periods of the experiment, in which case the 

 relation of the hybrid must be determined by the general 

 impression conveyed by the chart (see Chapter IV, page 

 168). However, in the vast majority of cases the 

 hybrid and parental relationships are presented quite 

 definitely. It will be seen that particular attention has 

 been given in the statements of intermediateness to note 

 whether or not there is mid-intermediateness, and if not, 

 the inclination to one or the other parent or both parents, 

 and it will be found that intermediateness is an exception 

 rather than a rule. In each of these sections the reaction- 

 intensities have been summarized in tabular form that 

 will be found of much value for comparative purposes. 



In the preceding sections the starches of the parent- 

 stocks and hybrid-stocks have been studied in their his- 

 tological properties and reactions with each of the various 

 agents and reagents, separately and comparatively, and 

 in a measure collectively; but as yet these reactions have 

 not been so presented as to give a clear picture, as it 

 were, of the reaction-intensities of each starch when 

 collectively considered and of each starch with the others 

 of the set. This has been attempted with a very large 

 measure of success in Section 6. Herein representative 

 reaction-values of each starch elicited by all of the agents 

 and reagents used are so linked as to form a composite 

 curve, and all three or four of the composite curves of the 

 si arches of the set are plotted out in the form of a single 

 chart. By this means there is afforded not only a method 



for the study of parental and hybrid relationships, but 

 also species, generic, and other taxonomic peculiarities. 

 The plan of plotting out these curves is described in 

 Chapter II, Section 12, and these curves are given fur- 

 ther consideration, especially from the aspect of plant 

 classification, in Chapter IV, page 172. 



It is of importance to note that in the gelatinization 

 reactions the values recorded are in terms of terminal and 

 not progress values that is, of the time of complete or 

 practically complete gelatinization within 60 minutes or 

 of the percentage of the total starch gelatinized when the 

 process is not or practically not completed within this 

 period. Therefore, when these values are compared 

 with those stated in Sections 4 and 5, where they are 

 based on reaction-intensities observed during the progress 

 of gelatinization, there may appear to be many discrepan- 

 cies of statement discrepancies that depend solely upon 

 different adopted standards of valuation. For instance, 

 turning to Chart E 1, the reaction-values of all four 

 starches in the chromic-acid and sodium-salicylate reac- 

 tions, respectively, are charted as being in each case the 

 same that is, in the former, complete or practically 

 complete gelatinization in 30 minutes and in the latter 

 in 5 minutes ; while in Sections 4 and 5 these starches 

 are differentiated in each of these reactions. The con- 

 struction of these composite charts is therefore mani- 

 festly seriously faulty, because important differences 

 recorded during the progress of the reactions are in part 

 or wholly ignored, for which reason such charts must 

 have only tentative and otherwise restricted values. 

 Notwithstanding such grave defects, they have a very 

 great measure of usefulness, and it is obvious from the 

 context that in their application to the recognition of 

 parents, hybrids, varieties, species, and g'enera, they 

 should be studied conjointly with the data of the preced- 

 ing sections of this chapter. 



1. COMPARISONS OF STARCHES OF AMARYLLIS BELLA- 

 DONNA, BEDNSVIGIA JOSEPHINE, BRUNSDONNA 

 SANDERCE ALBA, AND BRUNSDONNA SANDERCE. 



In form the grains of Brunsvigia josepliinfr in com- 

 parison with those of Amaryllis belladonna are less regu- 

 lar in outline and more varied in character, and unlike 

 those of the latter are somewhat flattened. There are 

 aggregates not found in the latter. Compound grains are 

 more numerous and are much more varied in form. A 

 type of compound grain is present that consists of two 

 small components joined by incomplete secondary lam- 

 ellae, sometimes by tertiary lamellae, that is not seen in 

 Amaryllis belladonna. Indentations of the margins of 

 the grains may be noted which are absent in the latter. 

 The hilum is more distinct and usually less eccentric. 

 The lamellae are not so fine, more distinct, much less 

 numerous, and the outermost tend, unlike in AmnryUis 

 belladonna, to be irregular and often not to follow the 

 outline of the grain. In size the average is less, and the 

 grains are broader in proportion to length than in the 

 latter. The polariscopic figure is, on the whole, con- 

 siderably less eccentric and less distinct; the lines are 



