128 



3. How is the root protected against injury? How does it absorb materials from 

 the soil ? What other functions does it perform ? 



4. Make a sketch of the important stages in the life of a fern, labeling the various 

 parts. 



5. In what respects does the seed of a Monocotyledon usually differ from that of a 

 Dicotyledon ? 



6. Mention the agencies that promote the distribution of plants, with illustrations 

 of the adaptive features. What factors control the association of plants upon the 

 earth ? 



7. Give the characteristics of six families of seed plants that you have studied. 



Popular Science Monthly for March contains an illustrated 

 article on the influence of radium rays on a few life processes of 

 plants by Professor C. Stuart Gager and a history of botany at 

 St. Louis by Dr. Perley Spaulding. 



The April Popular Science Monthly is a Darwin number with 

 numerous well-written articles on Darwin, his theories, and his 

 relation to the various sciences ; the one dealing directly with 

 botany is by Professor N. L. Britton. 



^\\^Reviezv of Revieivs for April has several illustrated articles 

 of botanical interest : one on soil erosion in the south by W. W. 

 Ashe, a second giving the " truth about dry farming " by C. M. 

 Harger, and a third on saving America's plant food by G. E. 

 Mitchell. 



An article on the existence of non-nitrifying soils is to be 

 found in Science for March 26. The authors, F. L. Stevens and 

 W. A. Withers, report that 44 per cent, of the samples tested 

 in North Carolina failed to nitrify, thus showing that all soils have 

 not the power to convert organic or ammoniacal nitrogen into 

 nitrate nitrogen, /. e., to nitrify. 



Science, for April 16, describes a series of large tanks now 

 being constructed at Cornell University. They are specially de- 



