SUMMARIES OF PLANT CHARACTERS, ETC. 



337 



2. THE PLANT TISSUES. 



MACROSCOPIC AND MICROSCOPIC CHARACTERS OF 

 HYBRID-STOCKS IN COMPARISON WITH THE REAC- 

 TION-INTENSITIES OF STARCHES OF HYBRID- 

 STOCKS AS REGARDS SAMENESS, INTERMEDIATE- 

 NESS, EXCESS, AND DEFICIT OF DEVELOPMENT IN 



RELATION TO THE PARENT-STOCKS. 

 (Table I, Parts 1 to 8, and Summaries 1 to 7. Charts F, 1 to 14.) 



Inasmuch as the macroscopic and microscopic char- 

 acters of plants are, like the microscopic characters and 

 reactions of starches, expressions of physico-chemical 

 processes, it follows, as a corollary, if starches exhibit 

 well-defined peculiarities in their parental relationships, 

 such as have been shown very clearly in preceding pages 

 that corresponding characteristics should be manifested 

 by the plant tissues. This is not only what has been 

 found, but also a remarkable congruity of the data con- 

 sidering the exceptional diversity of the methods of 

 investigation in the two entirely distinct although co- 

 operative lines of investigation. In the studies of the 

 starches the records show that each form of starch ex- 

 hibits in its histologic, polariscopic, and chemical proper- 

 ties varying relationships to the parents, some of these 

 properties (varying in kind and number in different 

 hybrids) being the same or practically the same as the 

 property of the seed parent, or of the pollen parent, or 

 of both parents; others being intermediate between the 

 corresponding properties of the parents ; and others 

 showing development in excess or deficit of parental 

 extremes. As exceptionally striking facts it was also 

 observed that the distribution of the data of parental 

 relationship under the six parent-phase divisions varied 

 with the different hybrid starches so markedly and 

 characteristically that each table of the characters of 

 each starch is diagnostic of the starch ; that the propor- 

 tions of intermediate and non-intermediate characters 

 vary within wide limits in different starches; that the 

 development of characters in excess or deficit of parental 

 extremes is more conspicuous than intermediateness or 

 sameness to either parent or both parents; and that the 

 comparative degree of influence of the seed and pollen 

 parents varied within extremes characterized by an almost 

 universal dominance of one or the other parent. Tables 

 F, G, and H give recapitulations and summaries of 

 the reaction-intensities of the starches of hybrids which 

 are not only exceptionally well adapted for comparisons 

 of certain fundamental data of the peculiarities of 

 starches, but also for bases of comparison of starch and 

 tissue characteristics. 



In Table I the macroscopic and microscopic data of 

 hybrid-stocks are formulated in correspondence with the 

 reaction-intensity data of the starches in Tables F and H. 

 Comparing in a general way the two sets of tables one 

 gets at first glance the impression of concordance, and 

 of so definite a character that it seems obvious that if 

 the two sets of tables were intermingled, the botanical 

 names having been removed, it would be impossible 

 to distribute them to their proper plant and starch 

 groups. The tissue tables differ from each other as do 

 the starch tables, and each is as individualized and diag- 

 nostic of the plant as is each starch table. In comparing 

 the data of Table 1 and its summaries the most con- 



22 



spicuous features are: The general or gross agreement 

 between the figures of the corresponding columns ; the 

 small number of characters and reactions that are the 

 same as one or the other or both parents in comparison 

 with the number that are intermediate, highest, and low- 

 est ; the distinctly smaller number that are intermediate 

 in comparison with the combined numbers that are 

 highest and lowest ; the comparatively small number that 

 are intermediate (in view of intermediateness being a 

 criterion of hybrids) ; and the many or less marked 

 dissimilarities in the distribution of the macroscopic and 

 microscopic data among the six parent-phases. In mak- 

 ing these comparisons it is preferable to take percentages, 

 inasmuch as the numbers of characters and reactions 

 are not the same. 



Referring to the first summary, it will be found 

 that of the 959 tissue characters 17.8 per cent are the 

 same as one or the other parent or both parents, and 

 that 82.2 per cent are intermediate, highest, and lowest; 

 while with the reactions of the starches (Table F) the 

 figures are 36.2 and 63.8 per cent, respectively, the 

 ratio of the former being 1 : 4.7 and of the latter 1 : 1.8. 

 Comparing the figures of the corresponding columns of 

 the two tables, the following percentages will be noted, 

 the first figure being for the tissues and the second 

 for the starches: Same as seed parent 5.8 and 13.4; 

 same as pollen parent 6.8 and 9.2; same as both parents 

 5.2 and 13.6; intermediate 43.2 and 23.2; highest 24.9 

 and 18.4; and lowest 14.1 and 22.2. Intermediate char- 

 acters in the tissue represent 43.2, and highest and lowest 

 characters 39, compared with 23.2 and 40.6 in the reac- 

 tions, showing in both cases that the percentages of 

 characters and reactions developed in excess or deficit 

 of parental extremes are very large, and in the reactions 

 very much larger than the intermediate percentages. It 

 therefore would seem to follow, as a corollary, that if 

 intermediateness is of given value as a criterion of hy- 

 brids, development in excess and deficit of parental 

 extremes is a criterion of greater value. 



One of the most unexpected features exhibited by 

 these data is the presence or absence of close correspond- 

 ence in the form of distribution of the macroscopic and 

 microscopic characters among the six parent-phases. One 

 would naturally be led to the assumption that if, for in- 

 stance, a given percentage of macroscopic characters 

 were the same as those of the seed parent a similar or 

 very closely similar percentage of microscopic characters 

 would fall under the same heading ; but, strange enough, 

 there may be a range of relationship between almost or 

 practical identity and very marked divergence, and even 

 inversion, of the percentages of the two groups of 

 characters. Thus, in Ipomcea sloteri (Chart F 1, Table 

 I, Part 1 and Summary 1) there is in general closeness of 

 the two curves, the only marked variation being in the in- 

 termediate characters. The percentages of characters 

 that are the same as those of the pollen parent and both 

 parents, and that are developed in deficit of parental 

 extremes, are in each case very close. The percentages 

 of macroscopic characters under each of these parent- 

 phases is lower than the corresponding percentages of 

 microscopic characters except in intermediate characters. 

 In the latter the percentages are not only markedly dif- 

 ferent (macroscopic 47.4 and microscopic 32.6), but 

 there is also an inversion of the percentages, and there- 



