61 



tree, of one species prospers, where one of another species re- 

 fuses to grow, a credible explanation may be found in the 

 knowledge that one may be a surface feeder ; and the other 

 one of a class that obtains nourishment from a greater depth. 

 However the subject is viewed, there are difficulties, more 

 especially when we consider that all around, trees of the 

 very same species, we have a difficulty about, are growing 

 and flourishing. I think we may safely infer that in each 

 of the reasons above given there is undoubtedly much 

 truth ; each circumstance probably contributes its quota 

 to the difficulty, and I think in regard to the fact that full 

 grown trees continue to flourish where young ones refuse 

 to come on, we may even venture to conclude that the theory, 

 that plants actually have the power of directly contributing 

 towards the operation of "cooking their own food" must 

 have some truth in it. If this be allowed we might argue that 

 a particular class of tree having been grown on a certain 

 spot that it had exhausted all the essentials of plant food 

 which were in a state favorable for immediate assimilation, 

 a nd that a young tree had not sufficient development to at- 

 tack the remaining store of crude inorganic constituents 

 which a fully matured tree had no difficulty in doing. 



A change in the variety of plant frequently is attended 

 with most satisfactory results, and it is a well known fact, 

 that in all Garden cultur e and even in Forestry, many expe- 

 dients are resorted to, in order to obviate the well known 

 difficulty of raising Supplies. The vacancies in a Hawthorn 

 hedge are often supplied with a Black -thorn, or even with a 

 Bramble; and after an Oak Forest has been felled there is 

 still a fortune to be made with Larch or Fir or kindred species 

 of soft wooded trees. Some few years ago I was attending on 

 an eminent Professor who was conducting a Chemical analy- 

 sis of some soil with a view of ascertaining what was defici- 

 ent after Coffee had been grown for a number of years. I 

 had supplied him with samples of virgin, and so-called, ex- 

 hausted soil, and the analysis had been most scientifically 

 and carefully conducted. I awaited the verdict in almost 



