188 



been changed ; it does not so hastily put confi- 

 dence in our treacherous spring ; and, advancing 

 more cautiously, escapes destruction. 



An instance somewhat analogous, illustrative 

 of the consequences of the labour of man, and 

 shewing how great may be its results, is detailed 

 by Sir Joseph Banks, who thought that many 

 plants might, by cultivation, become inured to a 

 climate, soil and situation, foreign to their ori- 

 ginal habits : and certainly many circumstances, 

 received as truths by the generality of horticul- 

 turists and vegetable physiologists, seem to war- 

 rant our acceptance of his theory. 



" In the year 1791," says Sir Joseph, in the 

 first volume of the Transactions of the London 

 Horticultural Society, " some seeds of the ziza- 

 nia aquatica were procured from Canada, and 

 sown in a pond at Spring-grove, near Hounslow ; 

 they grew and produced strong plants which 

 ripened their seeds. These seeds vegetated in 

 the succeeding spring ; but the plants they pro- 

 duced were weak, slender, not half so tall as 

 those of the first generation, and grew in the 

 shallowest water only ; the seeds of these plants 

 produced others the next year, sensibly stronger 

 than their parents of the second year. In this 

 manner the plants proceeded, springing up every 

 year from the seeds of the preceding one, every 

 year becoming visibly stronger and larger, and 

 rising from deeper parts of the pond, till the last 

 year, 1804, when several of the plants were six 



