ON THE POOD OF FISH. 125 



naturally producing those requisites whicli are the 

 most favourable to their production. Of course judg- 

 ment must be exercised ia carrying out such experi- 

 ments, quite as much as would be exercised in the 

 introduction or cultivation of a new food-producing 

 plant in agi'iculture. We acclimatise every species 

 of agricultural plant, and examine its qualities and 

 capabilities, for cattle or for ourselves ; we study 

 the soil and manure suited to it, &c. &c. ; we have 

 shows and prizes for the best specimens of agricul- 

 tural productions, and thousands of persons assemble 

 to note and study them ; but who ever thinks of 

 acclimatising an apparently worthless water-weed ? 



All plants, even to the meanest looking weed, 

 have their uses for man; and among the fauna of the 

 world, there must be many which would fee valuable 

 to us in the light above indicated. We have received 

 one from America — the anacharis alsinastrimi. This 

 weed has hitherto been a terrible nuisance, growing 

 so rapidly as to fiU up our smaller rivers and ponds 

 in many instances in an incredibly short time ; but 

 it might be that this weed, so troublesome and so 

 difficult to eradicate in the south, would be a great 

 benefit to the hill and moor lakes of the hard north. 

 Hardy water-plants, in which insects can thrive, are 

 greatly wanted there ; and it might be found that 



