R. P. Gregory 113 



experiments the distribution of the two kinds of stigma among the two 

 classes of colours follows the normal 9:3:3:1 ratio, being : 



MagenU MagenU Red B«d 



green stigma red stigma green stigma red stigma 



Fall colours 

 Sirdars 



Totals 

 Expectation 



In the later experiments there is considerable departure from this 

 distribution, the first class being small and the last large. But it is to 

 be noticed that in these two cases there is considerable departure from 

 the normal ratio of 3 : 1 in each of two pairs of characters under con- 

 sideration, the numbers observed being 77 magenta, 33 red ; and 78 

 green stigma, 32 red stigma. There seem to be no grounds for regard- 

 ing this discrepancy as other than a chance departure from the normal, 

 but it of course has a very material effect on the numbers observed in 

 the four groups when the two pairs of characters are considered in 

 conjunction with one another. If the theoretical ratio of 9 : 3 : 3 : 1 

 be weighted so as to allow for the two discrepancies a fairly close 

 approximation to the observed numbers is obtained : 



There is therefore no clear indication that partial gametic coupling 

 between the factors for magenta and green stigma occurred during the 

 gametogenesis in the ^j plants used in these experiments ; the point is 

 of some interest because partial coupling of these two factors is clearly 

 indicated in many of the experiments in which " Crimson King " 

 was used. 



" Crimson King " x Rosy-Magenta. The F^ from this cross is a 

 magenta of a rather deeper kind than that of the Fi from (" Crimson 

 King " X " Snowdrift "). In the F^ there occurs, in addition to the 

 ordinary magentas and reds, a curious parti- coloured type in which 

 irregular masses of full colour are distributed over a lighter ground. 

 These " Strawberries " (Plate XXXI, fig. 49) apparently belong to the 

 red class and only occur in small numbers, probably as one in 64 of 

 the total offspring. 



The magentas and reds may be subdivided into classes differing 

 from one another in a minor degree. Thus, in the red class there 



