26 BREEDING 



yellow before it ripens. This change in colour 

 is not the same as that which ripening pods undergo ; 

 or, if it is, it is the same change shifted back in 

 development, because it takes place long before the 

 pods begin to dry and ripen. This turning yellow, 

 whilst the plant is still juicy and growing, affects the 

 stem and, afterwards, the leaves, as well as the 

 pods ; and if seed of yellow-podded and ordinary 

 green-podded plants are sown together the numbers 

 of the two kinds of plants can be counted more 

 conveniently by the stems than by the pods, so 

 pronounced is the difference between the colour of 

 the green and that of the yellow stems. In Fig. 10 

 there is seen, to the left, part of a plant of the yellow- 

 podded variety ; and, to the right, a specimen of 

 the ordinary green-podded kind. In the yellow- 

 podded specimen, the pods themselves have gone 

 yellow, but the leaves are still green ; the contrast 

 between the pale colour of the pod and the deeper 

 colour of the leaf is clearly shown. The pod looks 

 as if it were made of yellow wax ; and the analogous 

 yellow-podded dwarf bean is sometimes called the 

 wax-pod bean. 



Mendel crossed a green-podded with a yellow- 

 podded variety of pea, and found that the offspring 

 were green-podded. The second hybrid generation 

 consisted of 428 plants with green pods and 152 with 

 yellow ones. A hundred of the green-podded plants 

 were tested, and forty of them gave rise to green- 

 podded plants only, and sixty to both green- and 

 yellow-podded ones. 



