16 VEGETABLE PHYSIOLOGY. [LESSON 5. 



LESSON Y. 



THE SUBJECT OF STAKCH CONCLUDED. GUMS AND SUGARS. 



87. It was found by experiment that 240 Ibs. of potatoes left in 

 the ground, contained of starch : 



In August. 23 to 25 Ibs. 



" September 82 " 88 " 



" October 82 " 40 * 



" November 38 " 46 " 



" April 88 " 28 " 



" May 28 " 20 " 



88. The quantity of starch remained the same during the dor- 

 mant state in Winter, but decreased as soon as the plant began to 

 grow, and to require a supply of nutriment. 



89. Starch exists in roots, stems, the receptacles of flowers, and 

 in pulpy fruits. The stem of the sago palm, the receptacle of the 

 artichoke, and the pulp of the apple, are situations in which starch is 

 found. 



90. Instances are not wanting in which starch, used for human 

 food, is found associated with the deadliest poison ; thus in Jatropha 

 manihot, a euphorbiaceous plant, the Indians, while engaged in ob- 

 taining the tapioca of commerce, or cassava-meal, dip their arrow- 

 heads in the fluid that exudes, to the intent that they may be thereby 

 poisoned. A more fatal poison is not known than the deadly milk of 

 this euphorbiacean ! 



91. Amongst the Cereals none are more valued for nutrient qual- 



FIG. 22. FIG. 23. 



Section of a grain of wheat Oryzopsis asperifolia, or Mountain Bice. 



ity than wheat; this appears to arise from another element abun- 

 dantly found associated with starch in this grain, viz., glfiten. A por- 

 .tion of a grain of wheat, highly magnified (Fig. 22), displays the 

 pericarp (a), -showing a number of vessels cut through; the epis- 



