328 PLANT PHYSIOLOGY 



QUESTIONS AND PROBLEMS 



1. How does the growth of plants differ from that of animals? 



2. When is the best season for making whistles from willow and hickory 

 wood? Why? 



3. If a nail is driven into a tree five feet from the ground in 1926, how high 

 will the nail be from the ground in 1936 if the tree grows six inches in length 

 each year? 



4. Why does the thickness of the cortex of a tree never reach that of the 

 xylem? 



5. All the wood of the stem which is produced in any one year produces 

 what type of geometrical figure? 



6. What are dandelion "curls" and how are they made? Explain. 



REFERENCES 



Blackman, V. H. — The compound interest law and plant growth. Ann. 



BoL, 33:353, 1919. 

 Denny, F. E. — Hastening the sprouting of dormant potato tubers. Am. 



Jour. BoL, 13:118, 1926. 

 Gustafson, F. G. — An explanation of the shape of the growth curve. Plant 



Physiol, 2:153, 1927. 

 Hanna, W. — The nature of the growth rate in plants. Sci. Ag., 5:133, 1925. 

 Hartshorn, R. — Some effects of acetylene on the ripening processes of 



bananas. Plant Physiol., 6:467, 1931. 

 Harvey, R. B. — Artificial ripening of fruits and vegetables. Minnesota Ag. 



Exp. Sta. Bui. No. 247, 1928. 

 Lillie, R. — Growth in living and nonliving systems. Sci. Mo., 14:113, 1922. 

 MacDougal, D. T. — Growth in organisms. Science, 49:599, 1919. 

 Growth as a problem in permeability. Cam. Inst. Yr. Book, 22:45, 



1924. 

 Reed, H. S. — Growth and sap concentration. Jour. Ag. Res., 21:81, 1921. 



Growth and differentiation in plants. Quart. Rev. Biol., 2:79, 1927. 



West, C.— Growth of the higher plants. Sci. Prog., 16:382, 1922. 



