Starch is one of the constituent parts in all mealy farinaceous seeds, fruits, roots, and other parts of plants, and is in large demand for domestic use, the arts, &c.  Our common starch is made from wheat, and a good deal from potatoes.  Pure fecula is separated by art from a variety of plants.

Of plants yielding starch we have the Indian arrowroot, which is the fecula in the rhizomata of several species of the Marantaceae.  In the West Indies it is obtained from the Maranta arundinacea, Allomyca and nobilis, and also from various species of Canna called Tous les mois, and in the East Indies from species of Curcuma, and from Maranta ramossissima in Silhet.

The bread fruit (Artocarpus incisa), already alluded to, yields a large quantity of starch; as do the sweet potato (Convolvulus Batatas, or Batatas edulis).  The pith or farinaceous part of the trunk of the Caryota urens, is almost equal to the finest sago.  In Assam the sago of this palm is much used.

The two varieties of the Cassava afford a very superior fecula, which is imported under the name of Brazilian arrowroot. 8,354 bags of tapioca and farina were imported from Maranham in 1834.  Some excellent starch from Norfolk Island was shown at the Great Exhibition.

The Cycadaceous family yields much starchy matter, along with mucilage.  From the soft stems of Cycas revoluta and C. circinalis, natives of China and the East Indies, a kind of sago is made.  These plants are propagated by suckers. Zamia pumila, a native of the Cape of Good Hope, and other species of this remarkable genus of plants, which is nearly related to both ferns and palms, supply an amylaceous matter, which has been sold as arrowroot.  A similar product is obtained from Alstroemeria pallida, a perennial plant, with pink red flowers, growing in Chili.  From the nuts of the Cycas circinalis, the Singalese prepare an inferior kind of starch, by pounding the fresh kernels.  These are cut in slices, and well dried in the sun before they are fit for use, otherwise when eaten they are intoxicating, and occasion vomiting and purging.

The quantity of starch in a plant varies according to the period of growth.  The results of examination on the comparative yield of starch in the potato, showed that while it abounded towards the latter part of the season, it decreased when the tubers began to germinate in the spring.  It was found by Professor Balfour that 240 lbs. of potatoes left in the ground, contained of starch—­

lbs.          Per cent. 
In August          23 to 25  or   9.6 to 10.4
September          32 "  38  "   13.3 "  16
October            32 "  40  "   13.3 "  16.6
November           38 "  45  "   16   "  18.7
April              38 "  28  "   16   "  11.6
May                28 "  20  "   11.6 "   8.3

The quantity of starch remained the same during the dormant state of winter, but decreased whenever the plant began to grow, and to require a supply of nourishment.