472 STARCHES OF AROIDEvE. 



is represented by P. undulata Raf. (P. virginica Kunth.), and popularly known as the arrow arum. 

 This starch closely coincides with the histological characters of the primary form of the Dieffenhnchia 

 grain (plate 15, figs. 87 and 88). It has a high degree of polarization, and the temperature of gelatiniza- 

 tion is 73 to 75C., mean 74. Starch was prepared from the bulbs of Colocasin var. escidenta Schott 

 {Caladium esculenta Schott), popularly known as the elephant's ear, and found to be in the form 

 of extremely minute grains of the Arum type grains too small for satisfactory study. A prepara- 

 tion from Amorphophalliis rivieri Dur., a plant known as the devil's tongue or the snake 

 palm, was also found to be in the form of small grains of the Arum type (plate 15, fig. 90). From 

 Alocasia pidzeijsi N. E. Brown (.4. watsoniana Hort.) a most peculiar kind of starch was obtained. 

 The grains in the original or natural form appear to be spherical or nearly so, and tend to break 

 apart into fragments which have sharp edges and angles (plate 15, fig. 89), and Avhich, raw or boiled, 

 become colored a wine-red with iodine. The degree of polarization was found to be quite variable, 

 being quite high in the intact grains and in some pieces or parts of pieces, to very low in others. 

 The interference figure was recorded as being somewhat eccentric, the lines intersecting in the 

 spherical grains to form a cross. The temperature of gelatinization was 62 to 63 C, mean 02.5. 



