32 THE SECRETIONS OF PLANTS STARCH. 



man. As a rule, a vegetable, if nutritious at all, is so in proportion to the amount 

 of starch which it contains ; but there are many plants which yield starch in tole- 

 rable abundance, but which are inedible from the presence of acid or poisonous fluids. 

 In selecting articles of food, it is needful to bear both these facts in mind. It is 

 most abundantly found in the seeds of plants, and especially in the cereals, or wheat 

 tribe ; and thence this article of diet is accounted to be very nutritious. It is also 

 met with in the cellular tissue of plants, and especially in the cellular matrix of 

 such underground stems as the potato, turnip, and radish, and the stems of such 

 plants as the sago-palm-fig, whence it is obtained in large quantities. Green vegetables 

 contain a considerable proportion of starch at the period of their maturity ; but they 

 are nutritive beyond the quantity of starch contained by them, since the vegetable 

 structure itself has a very similar chemical composition to that of starch. Starch is also 

 found in the bark of trees ; and, during periods of famine, the bark of certain trees in 

 this country has been made into bread. 



This practice ,was more common in the northern countries, where Nature has less 

 bountifully distributed her treasures. Mr. Laing, in his interesting " Journal of a 

 Eesidence in Norway," states 'that he observed many trees which had been thus dila- 

 pidated; and, after referring to the country mode of grinding meal, remarks " This 

 mode of grinding and baking makes intelligible the use of bread of the bark of the fir-tree 

 in years of scarcity. Its inner rind (liber], kiln-dried, may undoubtedly be ground along 

 with the husks and grain, and add to the quantity of meal it may even be nutritious. 

 I had previously been rather disposed to doubt the fact, and to laugh at the idea of a 

 traveller dining on sawdust pudding and timber^bread. In years of scarcity, however, 

 this use of fir-bark is more extensive than is generally supposed. The present dilapidated 

 state of the forests is ascribed to the great destruction of young trees, for this purpose, 

 in the year 1812." 



But, notwithstanding its universal distribution, it is to be found in quantities 

 only in the storehouses provided by nature viz., the seeds and fruit of plants ; the 

 potato (Solanum tubcrosum), carrot (Daucus carota), turnip (Brassica rapa), and similar 

 underground stems, as they arc termed ; and, lastly, the stems of palms, and similar 

 cndbffenotu plants. 



Amongst plants Avhich yield an acrid juice with the starch, we may first mention 

 the tapioca plant, or Yucca duke, the sap of which is used to poison the arrows ; 

 but the starch is fitted for food after the roots have been beaten, dried, heated, 

 washed, and pressed. The common arum of this country was formerly collected 

 on account of the starch or arrowroot contained in its corm or underground stem ; 

 but the aridity of the juice was so great as to cause the hands of the operator to 

 inflame. 



The horse-chestnut is not edible for the like reason, although it contains much 

 starch, and is excellent food for some inferior animals. It is also known that whilst 

 the tubers of the potato are so wholesome, the berries are poisonous. The horse- 

 chestnut was tried in this country as an article of diet in 1846, but its acidity arrested 

 its use. 



Those plants which offer the starch unmixed with deleterious matters are : 

 1st. All the grasses, including, wheat, oats, barley, rye, and all trinclar seed-bearing 

 plants. 



2. Many leguminous and cruciferae, or pod-bearing plants, such as the pea, bear., 

 and lentil, cabbage, and turnips. 



