No. 574] NOTES AND LITERATURE 



639 



appear. On Gregory's hypothesis recessive* should appear in 

 later generations. On the second hypothesis, homozygous races 

 of the types AAa'a' and aaA'A' would be obtainable, in appear- 

 ance like heterozygotes. These would breed true indefinitely 

 when selfed, but should give recessives in F, after crossing, as in 

 a case proved by Nilsson-Ehle. 



Sewall Wright 

 Bussey Institution, | 

 Forest Hills, Mass., , 

 June 19, 1914 jj 



NOTES AND LITEKATURE 

 A STUDY OF DESERT VEGETATION 1 

 Between three and four years ago Dr. W. A. Cannon, of the 

 Desert Botanical Laboratory at Tucson. Arizona, visited southern 

 Alucria in order to become acquainted with the more obvious 



