YALE AGRICULTURAL LECTURES. 41 



less these cambium layers of the tree and graft are brought 

 together, no union will result ; nor will there be one from the 

 contact of very different trees, such as a pear-graft on an oak. 

 The reason for this is, that the cellular tissues of the two are 

 so very different that there is no probability of making a fit, 

 any more than one can fit a sphere to an octahedron. Pears 

 graft well on quince, thornbush, and shadberry. They can be 

 grafted on the apple, but not profitably. The peach goes on to 

 the nectarine, and the plum to the cherry. There are instances 

 of natural grafting, as with the ivy when two branches cross 

 and rub the bark off so as to expose the cambium layers. Of 

 different grafts, of course the best is that which provides for 

 the greatest contact of the layers. 



Seeds are of varied vitality. Oily seeds do not keep well 

 because their oleaginous contents are liable to become rancid. 

 Thus the seeds of coffee, magnolia, clove, and such like, must 

 be soon planted or never. Seeds require warmth and moisture, 

 and if kept away from warmth, they often will keep for years 

 and years. Cucumber seeds have been kept seventeen years ; 

 corn, thirty ; French beans, thirty-three ; and from one bag of 

 seeds the Jardiu des Plantes was supplied with sensitive plants 

 for sixty years. 



To keep seeds well for the longest possible time, gather them 

 when fully ripe, and keep them cool and dry. How wonderful 

 the provisions of Nature for the dispersion of seeds ! Some are 

 furnished with feathery wings or silken down, with which they 

 float along on every zephyr ; others have barbed points, or 

 hooks, to catch and cling to passing animals ; others have elas 

 tic capsules or seed-bags, which, when brushed against, burst 

 suddenly apart and scatter the contents abroad ; and a thou 

 sand other methods might be named, alike curious and admi 

 rable. 



