STARCHES OF CUPULIFERiE. 

 NOTES ON THE STARCHES OF CASTANEA. 



437 



Such differences as have been recorded in the histological characteristics of these starches are 

 so trifling as to be practically useless in diagnosis. In the reactions the differences are in no case 

 marked, thus indicating a very close botanical relationship. Excepting the starch of Castanea 

 saliva var., which is of unknown source, it will be observed that there is close correspondence between 

 these starches, and that C. pumila stands a little apart, a distinction that is to be expected upon 

 the basis of the recognized botanical differences. 



NOTES ON THE STARCHES OF CUPULIFER^. (Charts 73 and 74.) 



The starches of the two genera representing this family show manifest relationships in their 

 various peculiarities. The histological likeness is quite apparent, but in Quercus are exhibited 

 larger grains, less irregularity in form, a relatively less abundance of nipple-like processes, and more 

 evident hilum and lamella;. There are also close correspondences in the reactions, but the composite 

 reaction curves of the two genera are sufficiently different to distinguish one from the other: In 

 Quercus the average degree of polarization is lower, the sensitivity to iodine greater, the temperature 

 of gelatinization higher, and the sensitivities to safranin, chloral hydrate-iodine, chromic acid, 

 pyrogallic acid, ferric chloride, and Purdy's solution in most instances are different from those of 

 Castanea. While, therefore, the histological differences are trifling, the reaction differences are in 

 the aggregate marked. 



Chart No. 74. 



P IGV T 

 S 



Composite Curve o( Mean Reaction-Intenaities of 

 Starch of Quercua. 



5 1 



10 2 



15 3 



20 4 



25 5 



30 6 



35 7 



40 8 



45 9 



60 10 



55 U 



60 12 



SS 13 



Composite Curve of Mean Reactton-'IntensitieB of 

 Starch of Castanea. 



