STUDIES OX THE GENETICS OF FLOWER-COLOURS, ETC. 101 



the segregation into 9 omnges ami 2 whites, wliich agree fairly well -witli tiie 

 calculated imiubers, S'"2.'j±l-lr.5 anil 2*75±l-43 respectively-, and may be 

 representetl \'\ Crf/f/rrhh, Avliilst another orange is homozygous and has the 

 constitution CCtjyt'i'hh. —As above stated, of three yellows of which I could 

 have examined the offspring one has thrown only 1 j-ellow, and is quite 

 iLseless f'jr our experiment. The second has segi-egated into 6 oranges and 1 

 wliito, .and since there will be no yellow which will show such segregation 

 without throwing any yellow at all, it seems to me to be probable that the I'atio 

 is here really 9 yellows : 3 oranges : 4 whites, of which no yellow did germinate 

 (i.e. CcGf/rrbb). The third has produced 5 yellows and 1 white : it lias 

 segi-egated eitlier in the ratio of 3 yellows and 1 white (i. e. CcGGrvbh), 

 or in that of 9 yellows, 3 oranges, and 4 wliites like the second, of which 

 no orange did germinate. No homozygoas yellow (CCGGi't'bb) came under 

 my oljservation, and this is not to be astonished, because we should have 

 only 1 such out of 9 yellows. Our conclusion is therefore that wo have in 

 our case in F. tlie 9:3:4 type of segregation, that the yellow variety has in 

 i^espect to its flower-colour one more factor than the orange, and that con- 

 sequently the cross between yellow and white-I varieties is based on the two 

 factors dillerence, ^•iz. C and G. 



Qx>33 III. Becl X orange and vice versa (PI 11, fig. 2 and 3). 

 CCltlibb X CCrrbb F, = CCRrhh 



The i^-hybrid has red flowei« whose colour intensity is almost similar to 

 that of the red pai'ent (s. the Table of Colours, p. 9(5). The i^-and i^j-oifepring 

 are composed as in Table III (s. p. 102) : — • 



As will be seen from this Table, though G out of 8 oranges have 

 given rise in F^ exclusively to oranges ( = 70), one of the remaining two has 

 thl•o^vn 3 oranges and 1 red, and another 5 oranges and 20 reds. Despite all 

 such facts these two orange parents (i. e. F^ plants) are considered to be 

 homozygous like all othere, so that all 8 oranges in Fj, are to be expressed by 

 the formula (Wvrbb (s. Table VIII, Nos. 19 and 11, and also discussions about 

 them in Chapter " Mutations, etc.," IV and II respectively, p. 128 and p. 127). 



Xs regards 11 reds in F-i whose behaviour in F^ I could have examined 

 6 were proven to lie ]n:no-, and 5 to be heteroz^'gous (expected, 365 



