more affected in this way than those which were protected 
by a stiff parchment layer. 
Example VII .—Native pea No. 2 crossed with a Sutton’s 
Satisfaction.” The former has coloured flowers and axils 
and very small smooth seeds. The testa has a greenish 
grey colour with fine purple dots, and in addition a 
; marbling or mottling of fairly extensive brown patches, 
like those exhibited by the English variety “ Maple.” Satis¬ 
faction has white flowers, nearly colourless testa and large 
wrinkled seeds. Satisfaction was used both as the “ male” and 
as the “female” parent. In the former case there was no 
change in the appearance of the seeds borne upon the native 
pea. In the latter nearly smooth seeds were obtained, which 
in other respects resembled those of Satisfaction. 
F, from both crosses showed red flowers and axils, and 
seeds coloured like the native pea, but these were slightly 
wrinkled (dimpled). 
Let us work out the expectation for colour of testa in F 2 
on the analogy of the previous Example (VI). 
Let A represent the coloured (greenish) testa, B the purple 
spotting, C the “ maple” marking.* For the colourless testa 
write abc. 
Fj—ABCabc produces the gametes ABC, ABc, AbC, Abc, 
aBC, aBc, abC,abc. If we expand the expression (A+2Aa+a) 
(B+2Bb+b) (C + 2Ce-|-c), and follow the supposition that 
both B and C can only appear when A is present, we shall 
expect in F 2 :— 
27 plants with maple, spotted, coloured testa ... (m.p.f.) 
9 plants with purple spots but no maple marks (p.f.) 
9 plants with maple marks but no purple spots (m.f.) 
3 plants with plain-coloured testa ... (f.) 
16 plants with colourless testa ... ... (w.) 
( 26 ) 
