MORPHOLOGY, GENETICS AND BREEDING 71 



Stok (74) to the present, who has not been able to isolate distinct 

 strains from within varieties. The 'question of selection within varieties 

 as opposed to selection within hybrid populations has claimed the at- 

 tention of peanut breeders. Men with long experience have maintained 

 that pure lines of peanuts tend to brealc down if selection pressure is re- 

 laxed. The instability of the pure lines may have arisen from (1) acci- 

 dental seed mixture (2) natural outcrossing, or (3) chromosomal insta- 

 bihty. The first possibility need not be discussed. According to Kushman 

 and Beattie (42) natural hybridization occurs with low but significant 

 frequency. In experiments designed to clarify this point numerous cases 

 in which crossing had occurred between Spanish and Valencia peanuts 

 were studied. The observed segregation of seed coat colors followed the 

 expected pattern. Three years of work demonstrated a small but definite 

 amount of natural crossing. Critical experiments of this nature have not 

 been conduct4¥e- by other workers so this is the only reliable published ac- 

 count. In contrast, the present senior author has observed the consistent 

 uniformity of hundreds of Fj and F^ plant progenies. These have included 

 many diverse families from experimental crosses grown side by side. If 

 further experimental evidence confirms the opinion that pure lines of pea- 

 nuts are unstable in the absence of selection pressure, this will be in 

 harmony with the known behavior of peanut chromosomes. Husted (38) 

 observed multivalent chromosome associations at first meiotic metaphase 

 and concluded A. hypogaea was a tetraploid. Mendes (44) confirmed 

 this in 1947. The number of chromosomes in cultivated peanuts is 2w = 

 40 wliile some of the wild species examined have 2« = 20, observations 

 which the writers have also made. The irregularities reported by Husted 

 (38) provide ample basis for predicting sporadic segregation from culti- 

 vated strains. 



Notwithstanding the fact that peanuts were subjected to genetic study 

 by Van der Stok (74) as early as 1910, only limited progress has been 

 made in the improvement of peanuts through breeding. With the advent 

 of World War I interest in peanuts as a source of vegetable oil stimulated 

 peanut-breeding activity. Thus in the United States reports of breeding 

 work began to appear about 1918, Beattie, private correspondence) . Al- 

 though the U.S. Department of Agriculture continued its efiforts through 

 the third decade of this century, active work at the various State experi- 

 ment stations did not begin until near its end. Breeding programs have 

 been reported as starting in Georgia in 1931, in Florida in 1928, in North 

 Carolina in 1929. During these years most of the work in Virginia, North 

 Carolina and South Carolina consisted of making individual plant selec- 



