280 TRANSACTIONS OF THE ILLINOIS 



absent. Lime plants can never be developed except on soils iu which that earth abun- 

 dantly occurs, and the same is true of potash and soda plauts. 



Upon these principles, the vegetation of extensive tracts of country has undergone 

 change in an artificial way. Thus, for example, in some of the Southern States, we may 

 pass for miles in succession, through tracts in which the ancient forest growths have 

 been replaced by the pinus toecla, or old field pin". These are tracts from which the pot- 

 ash salts have been removed by the culture of tobacco. This pine requiring the smallest 

 proportion of these salts, it therefore can flourish where the others cannot exist. 



One more illustration of the action of these physical agents must suffice. 



The Virginia cherry attains the height of a hundred feet in the Southern States, and is 

 dwarfed to a shrub of not more than five feet at the Great Slave Lake of the north, 

 lying far to the west of Hudson's Bay. 



Let us recapitulate. 



All vegetable organisms have their origin in a single cell — the mode of growth, size 

 and form of which is determined wholly by external circumstances. In all cases the 

 material for growth is obtained from without, and whatever the eventual shape of the 

 structure may be, the first ceil is in all instances alike. There is no perceptible differ- 

 ence in the first cell, which is to produce the lowest plant and that which is to bring 

 forth the giant oak of the forest, or unfold itself into the most beautiful flower. 



The mode of growth, and the arrangement of new cells, as they come into existence, 

 determining not only the form, but also the functions of the new being, depend on the 

 particular physical conditions under which the growth is taking place. Upon each 

 vegetable product natural agents exert their effects, pushing forward or retarding devel- 

 opment ; over the whole domain of life natural forces exert their sway. Change the con- 

 dition under which growth is taking place, and you at once change resulting form and 

 function; and it is in this manner that the horticulturist works in furnishing what are 

 called improved varieties of fruits and floAvers. And in passing to this more practical 

 part of our subject, we notice that propagation, through the agency of buds, consists 

 essentially in placing a bud of the plant, which it is desired to propagate upon a stock 

 nf a different kind, in such a way, that as development of the bud or cion takes place 

 union or incorporation with the stock shall occur. There are many different ways in 

 which grafting may be performed : they all depend for their success, however, upon 

 causing the alburnum of the cion to coincide with that of the stock, so that the vessels 

 of the former may receive the sap arising from those of the latter. 



When the parts are thus adjusted they are to be retained in their position by bandages, 

 or other suitable means, and protected from the air and rain by means of clay or wax. 

 The most suitable time for this operation must be Spring, just previous to the rising of 

 the sap. But one great leading fact must be remembered, for to forget it would bring 

 disappointment, with loss of time and money. It is this : If species of different natu- 

 ral orders be grafted they will not take. The stock and the scion must be nearly related 

 to each other, for there are certain limits within which the operation of grafting must 

 be performed. But if we take a bud and graft it in a stock of an allied kind, it will 

 eontinne to grow and develop in the same manner that it might have done without 

 detachmen f from the parent plant, and in the same manner from the new plant that 

 has thus arisen, by a repetition of the process, plant after plant, for many generations, 

 can be secured. 



Experience has taught us that, whatever might have been the peculiarity of the 



