No. XXXIV.] APPENDIX. 369 



found in tte composition of plants, they take it from tlie ammonia and 

 nitrates in the soil. 



Under all these conditions yon will succeed ; -without all these condi- 

 tions you can never be a successful horticnltuiist. 



We know how to grow our plants ; now what plants are we to grow, 

 and how ai-e we to obtain them ? In the first place we obtain them from 

 seeds. But what do we obtain from seeds ? A plant of a Kke species to 

 that from which the seed came. Of a Uke species, but likely to vary some- 

 what. There are certain limits to vai-iation, but those limits of variation 

 are marked. Take the wild ci-ab, which is so acrid that you cannot eat it : 

 compare that with the ribstone pippia. Thei-e is a wide difference between 

 them, but withia the limit of vai-iation. Take a vrild pear, compai-e that 

 with the deUcions pear of the present day, and the variation is enormous, 

 yet it is within the limit of variation, and horticiilturists have nevei- found 

 that one species transforms itself into another. I may say from experience 

 that I have never seen anything which could indicate to my mind that one 

 species of plant could be converted into another, and I do not believe that 

 there is any conversion of one into another, but simply that each species, 

 by itself, exhibits varieties which differ greatly sometimes, but are always 

 within the limit of variation, the progeny being only varieties of the same 

 species, and not being different species. This I believe to be the sum and 

 substance of all that is true of what is familiarly known as Darwinism. 



Well, we have then from our seed a plant with a certain likeness to 

 the preceding plant, but which has this difference, that members raised 

 from the seeds of the same plant exhibit certain peculiarities. We, thei-e- 

 fore, want to propagate any good variety that turns up ; how do we 

 proceed to propagate an improved variety ? Without knowing how to do 

 this we could not get on, and it is a matter of fundamental importance. 

 We want commonly to grow that which is improved ; how then shall we 

 propagate that improved variety which is turned up by accident or by high 

 cultivation ? In the first place, a convenient mode of propagating a plant 

 is by layering it. This is done by putting a part of the plant under the 

 ground, when it will take root and wiU be part of the original plant with 

 roots of its own, and you can cut it off and it then grows as an independent 

 plant, and that propagation of the original plant may take place to any 

 extent. Sometimes we want to propagate in a more remarkable manner, 

 and then we put part of one plant on part of another. This operation is 

 grafting. I cut off a shoot of one plant and put the shoot of another in 

 its place, then I have the last variety growing upon a stock of the fii-st. 

 It may be a saddle graft, where a notch is cut in one part to fit the other j 

 or it may be a whipped graft, where the two cut parts are side by side, or a 

 hole may be cut in the one and the other thrust into it. But there is one 

 condition on which only you can be successful : you must bring the new 

 wood of the one against the new wood of the other. By this process we 

 multiply any trees that we like upon another stock. 



Mien we propagate the same individual by the division of bulbs or by 

 dividing the roots, as in the Amaryllis tribe. You see then that when we 

 want to cultivate the same variety as we had before, we must not resort to 

 the seed, which may give us a plant with some slight difference from the 

 parent plant, and it is only by a special mode of propagation that we can 

 make any pai-ticular variety continue to produce the same variety year by 



2 B 



