152 BREEDING 



which have been folded back during the manipula- 

 tion are allowed to revert to their natural 

 position, one on either side of the carina, and 

 the standard also allowed to return to the posi- 

 tion natural to it in a bud of this age, shown in 

 Fig. 31. 



A bud treated in this way grows, opens, and 

 blossoms, then withers and dies, in exactly the same 

 way as a bud which has not been interfered with. 

 But the course of its subsequent history, as traced in 

 the characters of its progeny, has been profoundly 

 altered by what has been done. 



We are brought very close up against the mystery 

 of heredity when the extreme narrowness of the 

 channel through which the characters of organisms 

 have to find their way between each generation is 

 forced upon our attention, as it is by actually 

 making a cross between, say, a tall and a dwarf. 

 From the flower of a dwarf pea will grow out a pod 

 containing seeds all of which will be dwarf. But if 

 such a flower is deprived of its stamens and its pistil 

 covered with the pollen from a tall pea, all of its 

 offspring will be tall peas. We are thus firmly held, 

 without any possibility of escape, and forced to 

 recognise the fact that the character of the tall pea 

 is contained in each one of the pollen grains, them- 

 selves scarcely visible, as individual grains, to the 

 naked eye. This is how the problem of heredity 

 presents itself to the mind to-day : How are the 

 characters of the organism represented in the germ 

 cells which produce it ? The solution of this problem 



