GENUS DIEFFENBACHIA. 



471 



Differentiation of Certain Starches of the Cortex of the Genus Dieffenbachia. Continued 

 Effects of Various Reagents. 

 Reaclion icilh Chloral Hydralc-Iodine. 



D. seguinc var. nobilis: Begins in a minute; complete in 



12 minutes. 

 D. segiiine var. maculata: Begins in IJ^ minutes; com- 



[ilete in three-fourths of the grains in an hour. 

 D. seguine var. irrorata: Begins in a minute; complete 



in 2,') minutes. 

 D. illusiris: Begins in a minute; complete in three-fourths 



of the grains in 30 minutes. 



Reaclion with Chromic Acid. 



D. seguine var. nobilis: Begins in 30 seconds; complete 



in 4 minutes. 

 D. seguine var. maculnta: Begins in 30 to 60 seconds; 



complete in 5 minutes. 

 D. seguinc var. irrorata: Begins in 15 seconds; complete 



in 2 minutes. 

 D. illustris: Begins in a minute; complete in 4 minutes. 



Reaction with Pyrogallic Acid. 



D. seguine var. nobilis: Begins in 30 seconds; complete 



in 3 minutes. 

 D. seguine var. maculata: Begins in 30 seconds; complete 



in 7 minutes. 



Effects of Various Reagents. Continued. 



Reaclion with Pyrogallic Acid. Continued. 



D. seguinc var. irrorata: Begins in 15 seconds; complete 



in S minutes. 

 D. illustris: Begins in a minute; complete in 11 minutes. 



Reaction with Ferric Chloride. 



D. seguine var. nobilis: Begins in 30 seconds; complete 

 in 10 minutes. 



D. seguine var. maculata: Begins in IJ^ minutes; com- 

 plete in 30 minutes. 



D. seguine var. irrorata: Begins in 1 to 3 minutes; com- 

 plete in 22 minutes. 



D. illustris: Begins in 30 to 60 seconds; complete in 20 

 minutes. 



Reaction with Pxirdy's Solution. 



D. seguine var. tiobilis: Begins in 45 seconds; all the 

 grains piutially gelatinized in 30 minutes; incom- 

 plete in an hour. 



D. seguine var. maculata: Begins in a few in 2 minutes; 

 abouthalf the grains partially gelatinized in an hour. 



D. seguine var. irrorata: Begins in 2 minutes; complete 

 in only one-fifth in 45 minutes; the rest are par- 

 tially gelatinized; incomplete in an hour. 



D. illustris: Begins in 1 to 1}^ minutes; about one-fourth 

 partially gelatinized in IJ^ hours. 



NOTES ON THE STARCHES OF DIEFFENBACHIA. 



The fundamental or primary form of the starch-grains of Dieffenbachia is that of an elongated 

 elhpse, this being subjected to various modifications, cspeciallj' by the deposition of secondary 

 lamellte, so as to give rise to a considerable variety of shapes, some of them decidedly freakish. 

 In comparing the starches of the pith and cortex, it \vill be noted in the former that irregularities 

 in the forms are more conspicuous and that there is a greater tendency to larger grains in both 

 width and length (and disproportionately wider), than in those of the cortex. Some differences are 

 noted in the starches of the different varieties and species, e.g., the tendency to the hook-like form 

 in D. illustris, and the tendency to nodular deposits, particularly in D. seguine. In the reactions 

 it is of especial interest to note that each of the specimens differs sufficiently to be distinguishable, 

 and that while the pith and cortex starches of each variety very closely correspond they show differ- 

 ences that are more or less obvious. Thus, it will be seen that the pith starches compared with 

 those of the cortex have in each case a higher polarization, and either about equal or generally less 

 sensitivity to the reagents. With better methods differences would no doubt be brought out very 

 distinctly. 



NOTES ON THE STARCHES OF AROIDE^E. (Charts 92-96A.) 



The starches of the representatives of the five genera of Aroidew studied {Arum, Ariscemn, 

 Dracunculus, Richardia, and Dieffenbachia) belong to two entirely different types tjTies that seem- 

 ingly are so unlike as to suggest an absence of the family relationship set forth by the botanist. 

 The characters possessed in common by the first four genera are obvious, and it is equally clear 

 that Dieffenbachia must be set entirely apart. In general histological characters the starches of 

 the members of the first four genera might readily be mistaken, one for the other, but none could 

 be confounded with those of Dieffenbachia. WHiile it might be difficult or impossible to differentiate 

 the starches of these four genera by histological means, charts 92 to 95 show that the generic peculi- 

 arities are distinct; and by comparing further these charts with charts 96 and 96A, which exhibit 

 the reactions of the pith and cortex of Dieffenbachia starches, there is observed a general correspond- 

 ence as regards the type of curve, but the reaction-differences between the starches of the first four 

 genera and those of Dieffenbachia are quite distinct. These data show that while the differences in 

 histological characteristics of the two groups are seemingly irreconcilable, the physical, physico- 

 chemical, and chemical properties are akin. 



The marked differences presented by Arutn, Ariscema, Dracunculus, and Richardia on the one 

 hand, and Dieffenbachia on the other, led to a cursory examination of starches of several other genera 

 oiAroidece,mc\\i6\\\g,vc]}veseni2ii\\esoiPeUandrn,Colocasia,Alocasia,iiT\dAmorphophallus. Peltandra 

 32 



