22 THE NURSERY. 



collar? The place of juncture of the stem and 

 root. I say the name calls for attention. The thing 

 signified need hardly take our time, because in a 

 structural sense there is nothing of it. We have 

 only stem or root according as we exactly locate 

 the place. The collar is no organ, it is the junc- 

 ture of by no means very dissimilar parts. There 

 is no special vitality here, no peculia^r seat of 

 vitality nor of vulnerability. 



" The parts of a tree grown above ground exposed 

 to the air have harder tissues, not because it is stem 

 as opposed to root, but from condition of growth. 

 The root tissues are softer only because kept con- 

 tinually in the moist earth. Witness the hardened 

 texture of the brace roots of Indian corn above the 

 surface of the earth. 



" The collar therefore as most commonly located 

 is simply the place of the stem or root coinciding 

 with the level of the soil this and nothing more. 



" Now let us see what the results are when two 

 living parts are joined by grafting or budding. 

 Practical men know that to succeed in these opera- 

 tions the inner bark of these two pieces must be 

 placed in contact. 



u In the case of root grafting in the winter this is 

 not so critically imperative, because the callus 

 spreads somewhat between the two pieces. But in 

 any case what is absolutely essential is to secure the 

 meeting of cells capable of growth on the one side, 

 with those similarly conditioned upon the other side. 

 The old wood does not in any sense whatever unite. 



