768 STARCHES OF IRIDACEiB. 



NOTES ON THE STARCHES OF BABIANA. 



The gross histological differences in these starches are of a very minor character and probably 

 of no real value in diagnosis. The starches differ, however, in every reaction, B. var. (Violacea) 

 having a higher degree of polarization, a higher reactivity with iodine and gentian violet, a lower 

 reactivity with safranin, a lower temperature of gelatinization, a lower sensitivity to chloral hydrate- 

 iodine and pyrogallic acid, and a higher sensitivity to chromic acid, ferric chloride, and Purdy's 

 solution. 



NOTES ON THE STARCHES OF IRIDACE^. (Charts 303 to 319.) 



From an examination of the descriptions and the plates it will be seen that the starches from 

 Itidacece include a number of distinct types characterized by their conspicuous forms. Among 

 the irises there are two distinct types, as already referred to under Iris. The starches of Morcea 

 and Homeria appear to be essentially modifications of one of the Iris types, and the same might be 

 said of the starch of Tigridia, but in the latter instance the departure is more marked. Iris, Morcea, 

 Homeria, and Tigridia are closely allied genera. Another distinct type is observed in Gladiolus, 

 and which is represented in more or less modified form in Watsonia, Tritonia, Freesia, Antholyza, 

 Crocus, Romulea, Sparaxis, Ixia, and Babiana. Finally, another type is apparent in Marica and 

 Gelasine, the form of the grains in one of them being, it appears, a modification of that of the other. 



In a comparison of the reaction-curves of the representatives of these genera, it will be noticed 

 that there are more or less marked generic differences throughout the members of the family, but 

 there is no grouping of the genera curves that corresponds with the grouping based on the histo- 

 logical characters. The reactions of each genus represented are definitely distinctive of the genus, 

 and it will be noted that while in some instances there is a closeness of the curves in closely related 

 genera, in others there is not. Thus, botanically. Iris, Morcea, Homeria, and Tigridia are closely 

 allied genera, but while there are likenesses in the histology of their starches the reaction-curves 

 do not show corresponding closeness. Gladiolus and Watsonia are botanically closely related, the 

 starches are histologically alike, and the reaction-curves are of the same type, one being a modifi- 

 cation of the other. Tritonia and Freesia are closely allied in botanical characteristics, and allied 

 in turn w'lthGladiolus and Watsonia. The starch-grains are very much alike, and the correspondence 

 in the reaction-curves is distinct. In Antholyza and Crocus not only are the starches of the same 

 histological type, but the reaction-curves have the same fundamental characters. Romulea is 

 closely allied to Crocus, but while the starches are of the same histological type the reaction-curves 

 show distinctive differences, the starch of the former being distinctly more resistant, but the 

 differences in the curves may be quantitative rather than qualitative. Marica and Cypella are 

 allied genera, and this is indicated both in the histology and the reactions of the starches. Sparaxis, 

 Ixia, and Babiana are all closely allied South African genera, and have the same type of grains and 

 the same type of reaction-curve. (See Prefatory Notes.) 



