No. 611] 



ALLELOMORPHS 



693 



gates is a normal expectation and not an experimental 

 error. 



TABLE III 



cessives is taken as 25 per cent.^ and in (II) as 21 per cent. 



Such an aberrant segregation ratio seems to be a con- 

 stant tendency all through the generations descended from 

 Family B. This is shown in Table IV in which the ex- 

 periments in the years from 1912 to 1915 are summarized. 



TABLE IV 



TlIL AlUKRWr ShGlJ( \riO\ li UU.^ ()>iMMI. IN 'IIU Yl VR> lillJ-19lo 



Air.iui, .n n-.ml m tlit- mWu-h} o\' partial tV'rtility of 

 sterile plants, llic .l.-c<'ii(lnnt ^ of Familir^ A and ]i ex- 

 hibited re.^pectively rehitioiis similar to tho<e seen in 1912. 

 (Family A was not traced after 1913.) A count of fertile 

 spikelets on sterile plants descending from Family B was 

 made in 1914 on 281 plants bearing a total of 101,412 

 spikelets. In this count the number of fertile spikelets 

 was 3,857, corresponding to 3.78 per cent, of the total 

 nuni])er of spikelets. The latter figure may be regarded 

 as tlio avoraofo fertility of sterile plants in the progeny 



