124 THE PRINCIPLES OP AGRICULTURE 



caustic potash form muriate of potash ; muriate acid and caustic soda 

 form muriate of soda, which is commonly known as salt, — that is, 

 it is common salt. 



184a. From a potato tuber which has lain in the air until 

 somewhat wilted, cut circular segments about one-fourth of an 

 inch or less in thickness. Place some of these pieces in water, 

 and others in strong salt solution. In a short time those in 



water become more rigid, while 

 those in strong salt water become 

 flaccid. The cell -sap of the po- 

 tato, containing some salts and 

 sugars in solution, is a denser 

 solution than the water, and the 

 flow of water is inward to the 

 denser solution; hence the pieces 

 absorb water. Of those pieces in 

 strong salt solution the flow of 

 water is outward, and the potato 

 segments lose some of their watei 

 and become flaccid. See Atkin- 

 son's "Elementary Botany," pp. 



13-18. 

 Fig. 35. Root-hairs, enlarged. . 



18aa. A cross-section of a root- 

 let in Fig. 35 shows the root hairs. These hairs are seen to be 

 prolongations of the outer or epidermal cells. 



185^. By germinating a bean, pumpkin seed, or wheat in 

 moss, or between folds of moist thick cloth, the root-hairs may 

 be observed. Fig. 36 shows the fringe of hairs on such a seed- 

 ling ; and Fig. 37 shows how the root- hairs attach the soil 

 particles to the root. For a longer account of root -structures 

 and root-action, compare Sorauer, "Physiology of Plants for the 

 Use of Gardeners," pp. 4-7. 



186a. Any one who has handled both green and dry fodder 

 has a general idea of how much water there may be in plants. 

 Why do apples and grapes and cabbages shrivel after they are 

 picked ? 



188a. A single epidermal pore is a stoma or stomate. The 



