546 Report on the harclij Fruits for 1837, 



danger in this important respect would no longer be matters of 

 doubt ; they would become clearly defined, leaving interme- 

 diately the path of safely, in which the most inexperienced could 

 scarcely err. It is true that many productions, fostered by the 

 hand of Experience, are at the present time brought, apparently, 

 to the utmost perfection ; but, in other instances, the same culti- 

 vator will meet with repeated failures, without being able to ac- 

 count for such. The time may not be far distant, when the 

 question, " How is this?" will admit of an easy solution; for, 

 when the above limits, as well as those of moisture and dryness, 

 light and shade, are clearly understood, failures will be of rare 

 occurrence ; or, when they do occur, will be referrible to some 

 unavoidable accident. 



If a wild plant, indigenous to the neighbourhood of London, 

 were to be artificially treated, or committed to horticultural care, 

 it would be found to live longest in a temperature corresponding 

 with that of the average of the respective seasons of the climate 

 of London ; and that temperature, or gradations of temperature, 

 in which a plant will live longest must, certainly, be the most 

 congenial. It might be made to grow excessively luxuriant for a 

 season or seasons ; but this would be at the expense of its vital 

 powers. For instance, excessive heat and moisture might be 

 applied (I do not mean anything like a tropical heat, but equal 

 to, or greater than, that of our hottest summers) : an excessive 

 growth would be the consequence ; and, if continued, the plant 

 would ultimately outgrow itself ; or if, previously to its termination, 

 the over-exciting causes were reduced to a mediuui, or perfectly 

 natural degree of stimulus, the exhaustion would appear after- 

 wards by a less than medium developement, in proportion to the 

 excess of former luxuriance. It is scarcely necessary to explain 

 that the above statement is to be understood chiefly as regards 

 the climate, and not other points of culture ; nor to imply that a 

 plant will not thrive better, and live longer, when freed from the 

 troublesome neighbours of its own or other species in its wild 

 state. Farther, I will venture to say, that, in four seasons of 

 equal temperature, and that temperature agreeing with the ge- 

 neral mean of the climate, the growth of indiijenous forest trees 

 will be greater (other circumstances being the same) than in four 

 years alternately hot and cold ; although thcTj may average the 

 same as the four of e(juable mean temperature. \i' this be not 

 the case, then the inference would be, that plants have not been 

 originally well adapted for their respective localities. 



The average heat of day and night being now pretty well 

 known in the climate of London, throughout every month in the 

 year, and for a long series of years, it follows, if the above 

 statements be correct, that we also know the exact limits of the 

 extremes which all indigenous plants will safely bear; and one 



