S. ('. Hahlani) Wi] 



In aiioth(*r cmHs of S<»li<l iukI Small ryv |M'<Miliar nitioM wfw 

 obUiiruil. though tho behaviour of (vrtnin n| th«' Fj h«'tvn»/y^<)UM 

 fainilit*»4 in(iinit4M| that thror t'actoi'H wt»n* aluo coikmtihmI. 



Thr rxist^'HCr nf two Hi>lst'<Mt) fartors prcMhirin^ ihr sjuiH viMihli- 

 ort'tH't. alono or in rontbination, is analu^Mus t^» th** cljissic (mm<' oI tin- 

 colour of wheat i^niins Mtu<li<'<l by Nils.s4»n-Khh' (IIM)H) .ind bv tin- 

 Howarris (1912). Thry foun«l that thr R«m| rojonr charactir in c.rtani 

 typi's wjus ihw t4> thrco sojianitc nnits f«»r red. NiJHson-EliJc also 

 ob8orvo<l that a bhvck konn'llo(| nat variety may |k>ss(ss nion* than nn«- 

 unit for black, t'arh unit alnm- U'int; able to pnMlucr the tvjMcal blark 

 colonr. 



Ono |M»int nnist htic In* cniphiusiztMl most strongly. The prrsmt 

 writ4'r, fvt'n if lu' h;Ls I'stablishiMJ little ronclnsivdy, hjis at l<*;ist drmoFj- 

 stnit^nl the inadvi.sjibility of fitting a series of results to the nearest 

 pntbible nitio. and then ;iscril)ini( exce.ss of defieieney of certain t.v|Ms 

 to chanci" or to tlu' small innnlx'r of plants t^i-own. 



The results t)btaine(l by I )r S[)illman are now <'.usily explained. 

 The Solid forms used by him must have be«n in constitution W H, h_, 

 or W h, H,. Kither of these would give an F, ratio of 9.S' : 8 M' : .S// : I S/^J, 

 when cr«>.s.sed with Small eye. 



III. The CoLorR of the Pattern of the Seed ('o.vt. 



(a) The /actor H. 



One of the pjirents of CnKss 1 , the Black eye variety, is characteri.sed 

 by the apjK'amnce of a <lark red or purple coloration on the tip of the 

 young jxxl. The colour first a|)pears when the pod is two oi- threr davs 

 old, and lasts until the [x>d is nearly ripe, when it is obscured by the 

 drying up of the \hm\ which then takes place. 



The red ti|) of the immature pod is a pt^rfectly distinct chamcter, 

 and is found to occur only in plants which pos.se.ss black colonition of 

 the t^^'St^i {);\tt4*rn. It is always accompanied by more «>r less n*d colour 

 in the calyx and jx-duncle. 



It has been |)ointed out by Morgan et al. (1915) thai a so-called 

 unit character is only the most obvious ov most significant product of 

 the j>Kstulat«d factor, and that a single factor may affect a plant or 

 animal in many different ways. An example of a single genetic difien-nce 

 which affects th.- <ntirc organization of a plant is seen in the jx-culiar 

 types known as (Vinkled I)warf Rogues which occur occiisionallv in 

 fields «»f Sea Island Cotton. Tli*- present wiitci- (19h))lias shown that 



