THE ROOT. 33 



roots, as those of Pandanus, commonly culti- 

 vated in conservatories, also have remarkably 

 developed root-caps. 



II. Conditions affecting the formation of root-hairs. 

 An interesting investigation is suggested by 

 Haberlandt, Physiologisclie Pflanzenanatomie, p. 

 147 et seq. 



III. Propagation of plants by slips and cuttings. Ascer- 



tain what plants are regularly propagated in this 

 way by florists and what conditions are necessary. 



IV. Reserve materials stored in roots. Examination of 



the blackberry, elecampane, and other roots, to 

 determine the nature of the food substances con- 

 tained in them. 



V. Influence of moisture on the direction taken by 

 roots. " Search for water " by roots of trees. 



VI. Minute anatomy of roots. (This may be deferred 

 with advantage until the stem is studied micro- 

 scopically.) 



VII. Estimate of the total length of the root system of 

 some common plants. Johnson, How Crops 

 Groiv, p. 242. 



VIII. Roots of parasites. Sections of roots of Comandra 

 or mistletoe, with a study of their relation to the 

 plants on which they have fastened. 



REVIEW AND SUMMARY. 



Roots function as organs of absorption, as storehouses of 

 reserve materials, and as a mechanical means of holding 

 the plant firmly in its place. 



