CANTO ii. REPRODUCTION OF LIFE. 57 



" So grafted trees with shadowy summits rise, 

 Spread their fair blossoms, and perfume the skies; 

 Till canker taints the vegetable blood, 

 Mines round the bark, and feeds upon the wood. 170 

 So, years successive, from perennial roots 

 The wire or bulb with lessen'd vigour shoots; 

 Till curled leaves, or barren flowers, betray 

 A waning lineage, verging to decay; 

 Or till, amended by connubial powers, 

 Rise seedling progenies from sexual flowers. 



" E'en where unmix'd the breed, in sexual tribes 

 Parental taints the nascent babe imbibes; 

 Eternal war the Gout and Mania wage 

 With fierce uncheck'd hereditary rage;. 180 



So grafted trees, 1. 167. Mr. Knight first observed that those apple 

 and pear trees, which had been propagated for above a century by 

 ingraftment were now so unhealthy, as not to be worth cultiva- 

 tion. I have suspected the diseases of potatoes attended with the 

 curled leaf, and of strawberry plants attended with barren flowers, 

 to be owing to their having been too long raised from roots, or by 

 solitary reproduction, and not from seeds, or sexual reproduction, 

 and to have thence acquired those hereditary diseases. 



I 



