28 



ARTIFICIAL PROPAGATION 



thorns, but it is an unwilling subject on the apple. Tomato 

 plants will grow on potato plants, and potato plants on 

 tomato plants. When the potato is the root, both tomatoes 

 and potatoes may be produced; when the tomato is the 

 root, neither potatoes nor tomatoes will be produced. Chest- 

 nut will grow on some kinds of oak. 



72. The forming, growing tissue of the stem (on the plants 

 we have been discussing) is the cambium, lying on the out- 

 side of the woody cylinder, beneath the bark. In order that 

 union may take place, the cambium of the cion and of the 



42. Cion of apple. 



43. The cion inserted. 



44. The parts waxed. 



stock must come together. Therefore the cion is set in the 

 side of the stock. There are many ways of shaping the cion 

 and of preparing the stock to receive it. These ways are 

 dictated largely by the relative sizes of cion and stock, 

 although many of them are matters of mere personal prefer- 

 ence. The underlying principles are two: securing close 

 contact between the cambiums of cion and stock; covering 

 the wounded surfaces to prevent evaporation and to pro- 

 tect the parts from disease. 



73. On large stocks, the commonest form of grafting is 



