STRUCTURE.] SIZE SITUATION. 121 



B. Small grains united round a much larger one. 

 22. In Sagus Rumphii, &c., in pith, mostly in sago. 



Starch is the most common of all vegetable productions. 

 I know of no plant that does not in some season or other, at 

 least in the time when vegetation is at rest, secrete starch in 

 more or less abundance, often only in single grains in the 

 cells, but often also swelling the cells from the large quantity 

 of it. The grains of starch adhere to the cell walls, for the 

 most part accidentally, by means of mucus. The supposed 

 hilum, by which the grains of starch have been said to be 

 held to the sides of the cell, is one of Turpin's innumerable 

 careless representations, and is entirely without foundation. 

 The largest starch-grain does not appear to be more than 

 0-05 of a line in the longest part. Starch can generally be 

 separated from the cellular tissue by bruising and washing 

 with water ; often, however, it cannot, as, for example, when 

 it occurs united to mucus, as in Hedychium. Starch seems 

 to be purest in Maranta arundinacea. It is not too much to 

 say, that for two-thirds of mankind starch is the most 

 important, if not exclusive, source of nourishment. It is 

 certain that starch occurs in all plants, but not always in 

 such a state as to suffice and become fit for food; it often 

 cannot be separated from other disagreeable substances, as 

 in the horse-chesnut. Certain parts of plants secrete it 

 more than others, viz., the albumen of the seeds (Grasses), 

 the cotyledons of the embryo (Leguminous plants), pith 

 (Cycads and Palms*), bulbs (Lilywortsf), tubers, rhizomes 

 and roots of several different orders.J In less abundance, 

 it is found throughout the winter in the bark and sap of 

 trees ; hence the possibility of making bread from the bark 

 of trees in polar countries. 



This very detailed account does not, however, touch the 

 important question of the source from which starch grains 



* Sago from Cycas revoluta, Sagus Rumphii, farinifera, &c. 

 f Liliuin camtchaticura used as food in Greenland. 



t Potato, from Solanum tuberosum ; Cassava, from Jatropha Manihot, Tarro 

 from Arum esculentum, &c. 



