110 HISTOLOGY OF ANGIOSPERM STEM, ROOT, ETC. 



arising as outgrowths of the central cylinder and passing 

 through the cortex to the surface, from which they pro- 

 trude examine several roots, to see various stages in the 

 development of the rootlets. 



127. Root-hairs. These should be examined in roots 

 of seedlings grown in damp air, in water, and in soil. In 

 Bean and Pea the hairs are readily seen in seedlings grown 

 in loose moist sphagnum (see 1 70) instead of soil. 



(a) Mount in water the slender roots of such seedlings 

 as Cress, Mustard, or Wheat, grown through muslin into 

 water, and examine the root-hairs with the high power. 

 Run in salt solution and note the plasinolysis of the cell- 

 contents. Treat with iodine solution, which will stain the 

 protoplasmic lining of the hair. 



(6) Grerminate Wheat grains in two pots of fine garden 

 soil, 4 or 5 grains to each pot. When each seedling has 

 produced 4 or 5 roots, turn out the soil of one pot and care- 

 fully remove the plants, noting the mass of soil adhering to 

 the roots ; shake the plant and note that most of this soil 

 falls away, but some of it remains clinging closely to the 

 roots, though the root-tip is free from soil. Einse the roots 

 in water, examine with the microscope, and note that the 

 tip of each root is free from root- hairs, which are abun- 

 dantly present over the rest of the root, and that the finer 

 soil-particles cling so closely to the hairs as not to be 

 removed by the rinsing in water. Let the other plants 

 grow for 5 or 6 weeks ; then remove a plant and note that 

 no soil -particles cling to the older parts of the roots, from 

 which the root-hairs have now disappeared. 



(c) Soak seeds of different plants e.g. Mustard, Wheat, 

 Pea in water until the radicle is 1 cm. long. In each 

 case get three tumblers or jars with muslin tied over the 

 mouth ; fill A with distilled water, B with culture solution, 

 and into G pour a little water to keep the air moist. 

 Transfer a seedling of each kind to each tumbler, and also 

 sow some (D) in a pot of good soil. Cover the tumblers 

 with a bell- jar, add water daily to make up for that lost 

 by evaporation and transpiration. After a week or two 



