284 The Inheritance of Wiug-Colowr in Le^ndoptera 



7'ustica X rustica. 

 [BD X DD\ 



Imagines 



Male Female 



•' Pure rustica " rustica and Type 



Family (PD) standfussi(DR) {KR) 



'l&D 28 — — 21 



'17 C 2 — — 2 



'18£ 5 _ _ 5 



Totals 35 — — 28 



the following table the F^ hybrid (/•(/ have all been included under the 

 heading "rustica and standfussi." Many of these (/'(/' were pale, but as a 

 rule they were not quite so pale as "pure rustica," or the DR insects of 

 families '16.4 and 'IdB (see Fig. 1). The very dark ^ (Fig. 3) with a 

 value of 40 is so black that it is probably a type insect included by 

 mistake. The average value for these Fj insects is seen from Fig. 4 to 

 be not much above I'O, so that it may be inferred the dominance of 

 7'ustica is nearly complete. 



rustica x Type. 

 [BB X RE]. 



Imagines 



Totals ... — 53 — 83 



The F2 generation, obtained by crossing two F^ insects, might be 

 expected to give approximately 7^ustica, standfussi and type, in the ratio 

 1:2:1. As the table on p. 286 shows, this appears to be the case, except 

 that the DD class is rather too large, owing of course to the fact that it 

 must contain a few white insects, indistinguishable from rustica, which 

 are genetically heterozygous (DR). In these circumstances the DR class 

 only contains standfussi ; and the DD class can only be called rustica. 

 Although the totals approach the expectation, the numbers in the indi- 

 vidual families seem to vary widely, and the fact that the ratio is so 



