VEGETABLE CYTOLOGY 



8l 



Compound grains more or less rod- 

 shaped. 



2 to 15^1 in diameter. 

 Hilum: central. 

 Lamellae : generally indistinct. 

 Polarization cross distinct. 



Cassava Starch (Manihot 

 utilissima) 



Grains rounded, truncated on one 

 side. 



Simple or two- to three- or four- to 

 eight-compound. 



6 to 35/x in diameter. 



Hilum: central, circular or triangu- 

 lar with radiating clefts frequently. 



Lamellae : indistinct. 



Polarization cross prominent. 



Bean Starch (Phaseolus vulgaris) 



Ovoid, ellipsoidal or reniform shaped- 

 simple grains, occasionally ob- 

 scurely 3- or 4-sided. 



25 to 60 fj. in length. Generally from 



30-35M- 



Hilum: central, elongated with bran- 

 ching clefts. 



Lamellae: distinct, concentric. In 

 some indistinct. 



Polarization crosses shaped thus, X 



Pea Starch (Pisum sativum) 

 Oval-oblong, ellipticolar sub-reni 



form. 

 I S~S I M i* 1 length. Generally from 



Hilum: similar to that of bean 

 starch but less cleft or simply 

 elongated. 



Lamellae: distinct, concentric. 



Polarization crosses similar to bean 

 starch. 



Canna Starch (Canna edulis and other 



species of Canna) 

 Broadly elliptical, flattened, with 



beak or obtuse angle at one end. 

 50 to 135/i in length. 

 Hilum: excentric near narrower end. 

 Lamellae: concentric and excentric. 

 Polarization cross very distinct; fine 



play of colors with selenite plate. 



Sago Starch (Metroxylon Sagu] 

 Ovoid, muller shaped, or irregularly 



3 or 4 sided with rounded angles. 



Some more or less gelatinised. 

 Simple or 2, 3 or 4-compound 

 3<>-6oju long. 

 Hilum: eccentric often altered by 



gelatinisation. 



Lamellae : Excentric and concentric. 

 Polarization cross distinct. 



4. Dextrin. Dextrin is a carbohydrate made from starch (chiefly 

 from corn or potato starch) by the application of heat (yellow 

 dextrin) or by treatment with both heat and acids (white dextrin). 

 It forms a paste with water, the yellow variety tending to swell up 

 and dissolve much more readily than the white. When examined 

 microscopically in alcohol mounts, the grains, while conforming in 

 general outline to those of the type of starch from which the dextrin 

 was prepared, nevertheless show more conspicuous striations and 

 clefts. . Corn dextrin shows distinct striations, whereas striations 



6 



