[Chap. XXXIX MUTATIONS 489 



Cooper, D. C. Artificial induction of polyploidy in alfalfa. Amer. Jour. Bot. 

 26:65-67. 1939. 



Crane, M. B., and W. J. C. Lawrence. The Genetics of Garden Plants. 2nd 

 ed. The Macmillan Company. 1938. 



Demerec, M. Unstable genes. Bot. Rev. 1:233-248. 1935. 



Goodspeed, T. H., and Fred M. Uber. Radiation and plant cytogenetics. Bot. 

 Rev. 5:1-48. 1939. 



Jones, W. N. Chimeras: a summary of some special aspects. Bot. Rev. 3:545- 

 562. 1937. 



Lindstrom, F. W. Genetics and polyploidy. Bot. Rev. 2:197-215. 1936. 



Muller, H. J. Why polyploid\' is rarer in animals than in plants. Amer. Natu- 

 ralist. 59:346-353. 1925. 



