STARCH. 1s 
dium speciosum, Willd. Sago-starch’ is provided with swollen 
protuberances (Fig. 42). Independent of exceptions of this 
character, the spherical and ovate, or often flattened forms? pre- 
dominate. 
Although not susceptible of strictly mathematical definition, 
the size and shape of the starch granules are nevertheless char- 
acteristic for individual plants. A knowledge of these peculiar- 
ities is therefore indispensable in the examination of flour and 
varieties of starch. Besides the smaller structures, which usu- 
ally occur, each granule possesses a predominating typical form. 
It is only when the latter has been confirmed, in its definite 
shape and size,* by a large number of granules, that one can 
assume that a certain variety of starch is present. 
In the examination of starches, this is the only means for 
Fic. 42. 
Fic. 42.—Starch granules of Sago (Hager). 
Fie. 43.—Potato starch (Koenig). a, the nucleus. Compare also Fig, 108. 
their identification, but it is otherwise with varieties of flour. 
The latter consist of ground fruits and seeds, and thus con- 
tain, besides the starch granules, remnants of cells of the inner 
tissue as well as of the integuments, and often also remnants of 
hairs (Zriticwm). In the case of flour, these remnants may 
therefore be very well used as a guide in their examination.* 
* Compare also Wiesner, ‘‘ Die Rohstoffe des Pflanzenreiches,” Leipzig, 
1873, 
* For example in Zingiber, Berg’s Atlas, Plate xx., 49. 
* Measurements of the size of the granules (by the aid of the ocular 
micrometer) must always be undertaken. The linear diameter is deter- 
mined. The unit ‘of measure is the micro-millimeter ( or mic.) = 
reop Mm. = 0.000001 m. a 
* Compare ied nies, ‘* Anleitung zur Erkennung organischer und 
