KEACTION-INTENS1TM :> \\ini KM H AGENT AND REAGENT. 



167 



reagent ; that the reactions of a given starch may vary 



with ilittVrent agenU and reagents within wide iimiU; 



that there U a manifest tendency to groupings of reac- 



t>on-inteiiMties of different starches that are, on the 



whole, very closely in harmony with tin- plant groupings 



iif the systematic; that the most ranahlu relationships 



U'twevn the Htarches in their reaction-intensities, 



as regard* sameness, intermediateneM, excess and delicit 



:i-intcn>ity ile\cl"pineiit of the hyhrid in rela- 



tiiin t thi- reactions of thr parent*; ami that tho ditTer- 



enoea in the reaction* are conditioned l.v differences of the 



tarch niulei ulc. l>y the characters of the agents, and by 



ular ctin.tituti"ii and concentration of the reagents. 



imparative ttudie* of the reactions with the chemi- 



.1 r. H.-eiit.- have as their sole basis values that are ex- 



pressed in t. rms of percentage of atarch gelatinized in 



60 minutes or leas. There waa no note regarding dif- 



t-s that were recorded in the comparative percent- 



ages of the entire number of grains and total starch 



gelatinized at definite time-intervals, and only the most 



:1 references were made to peculiarities observed 



in the progress of curves of the reactions from period 



l>oth of these features are found to be of 



importance, alone and in conjunction with the 



:tgs presented in the foregoing sections, in the de- 



termination of generic, species, varietal, parental, and 



hybrid peculiarities of starches. The reaction-intensi- 



f different starches with different reagents recorded 



in Cart II, Chapter I, include the percentages of both 



.tire grains and total starch gelatinized at definite 



intervals. The data of the total starch gelatinized 



een tabulated in Section 3 of each of the Compari- 



sons of the Stan lies of the Parent- and Hyhrid-Stocks 



in Chapter III, and they are here presented with few 



unimportant exceptions in the form of Charts D 1 to 



i which admirably exhibit both intensity and 



*$ of the reactions, and render comparisons of the 



f both starches and reagents very satisfactory. 



I charts (Charts I) 635 to D 691) have been 



laced to show the relationships between the per- 



centages of entire grains and total starch gelatinized at 



given MM. -intervals. There will also be found among 



.tftti, LUium, and Begonia a few charts that show 



differences between these percentages, and a few addi- 



tional charts to bring out certain generic peculiarities. 



These charts are so very numerous and the curves so 



':n-ly \arie<l that detailed descriptions and coro- 



na are rendered impracticable because of necessary 



itions of space, although it will be perfectly mam- 



ifter even a superficial survey, that the recalls of 



such a study would prove of great value in many direc- 



tion* much that is of more than mere passing 



interest, value and suggeativeneM can be brought out by 



even casual examination. 



I'KRCEXTAOR or TOTAL STARCH GKLATIXIZED AT 

 DEFINITE 



(Chart* D 1 to D 034.) 



The curves of total starch gelatinized vary widely 

 and the number and forms of types recognized are purely 

 arhitranr. In some instances the curre is nearly or 

 absolutely rectilinear, but in moat cases it U circnmli'm ar 

 and varied, but suggestive usually of an ellipse, hyperbola 



or parabola or some modification of one of the three. 

 The rectilinear curves are presented in the form of three 

 type* or what may tentatively be regarded as three modi fi- 

 ns or forms of a single type: 



(a) A form that is characterized by an immediate, 

 very rapid and continually rapid rise of the curve at an 

 angle approximating about 1" to 2 with the verti- 

 cal, thus representing a complete or practically com- 

 plete gelatinization in 1 or 2 minutes. This curve 

 should probably be cm-unilinear inasmuch as it is likely 

 that during equal increment* of time larger increments 

 "f the HUn-h are gelatinized during the earlier than later 

 periods of the reactions, but the time-intervals here are 

 too short for such determinations. This belief is sup- 

 ported by the fact that when the reactions of the aame 

 starch but with a weakened reagent are somewhat less 

 rapid, as when complete gelatinization occurs at the end 

 of 5 minutes, this variation is noted and the circumlinear 

 character of the curve is quite marked, the increments 

 of gelatinized starch falling very rapidly and dispro- 

 portionately after the first minute. This form of curve 

 is illustrated in the Amaryllii-Krurutvigia-Brurudonna 

 group in the reactions with nitric acid, sulphuric acid, 

 hydrochloric acid, and potassium hydroxide (Charts 1) 4, 

 D 5, D 6, and I) 7). It will be seen that in fome of the 

 reactions the line is straight and in others curved. 



(6) Another form of the rectilinear type presents a 

 curve that is almost if not entirely rectilinear, but having 

 an inclination that rarely is less than an angle of 80" 

 with the vertical, which is equivalent to a maximum of 

 approximately 15 per cent of the total starch gelatinized 

 in 60 minutes. This form of curre is associated usually 

 with weak gelatinizing reagents and exceptionally re- 

 sistant starches. It will very frequently be found in the 

 study of these charts that while a given starch may show 

 such a curve with one reagent, a curve of the first form 

 or of an entirely different type may be exhibited with 

 another reagent. Such a curve is well typified in the reac- 

 tions of Brwwdonna tandera alba with sodium sulphide, 

 cobalt nitrate, cupric chloride, barium chloride, and mer- 

 curic chloride (Charts D 12, D 17, D 19, D 20, D 21). 



(e) A third form of the rectilinear curve links in its 

 varied positions the first and third forms, and were it not 

 that the first two forms are very common and the third 

 form relatively rare, there would be no good reason for 

 the recognition of three forms. This form is illustrated 

 in the reactions of Hrunsrigia josephina with mercuric 

 chloride (Chart D21), of Crinum Icircape with sodium 

 sulphide (Chart D 159), and of N trine bowdeni with 

 uranium nitrate (Chart D 225). 



The circumlinear type of curves is divisible into three 

 forms: 



(a) One form shows that gelatinizatinn begins and 

 proceeds rapidly, there being progressively or practically 

 progressively decreasing increments of starch gelatinized 

 with additional increments of time. This form is illus- 

 trated in the reactions of Amaryllu belladonna with 

 sodium sulphide (Chart 1)12). This form of curve is 

 very common, perhaps the most common of all. An 

 examination of this aerie* of charts (Charts Dl to 

 D 634) will elicit most varied and modified gradations in 

 both directions from what may properly be regarded as 

 a true hyperbolic form. 



