CUKCULIO FOUND IN WARTS. 79 



Journal." The grubs, found by Professor Peck in the tumors 

 of the cherry-tree, went into the ground on the 6th of July, 

 and on the 30th of the same month, or twenty-four days 

 from their leaving the bark, the perfect insects began to rise, 

 and were soon ready to deposit their eggs. 



The plum, still more than the cherry tree, is subject to a 

 disease of the small limbs, that shows itself in the form of large 

 irregular warts, of a black color. Professor Peck referred 

 this disease, as well as that of the cherry-tree, to the agency 

 of insects, but was uncertain whether to attribute it to his 

 cherry-weevil " or to another species of the same genus." 

 It was his opinion, that "the seat of the disease is in the bark. 

 The sap is diverted from its regular course, and is absorbed 

 entirely by the bark, which is very much increased in thick- 

 ness ; the cuticle bursts, the swelling becomes irregular, and 

 is formed into black lumps, with a cracked, uneven, granu- 

 lated surface. The wood, besides being deprived of its nutri- 

 ment, is very much compressed, and the branch above the 

 tumor perishes." Dr. Burnett rejected the idea of the insect 

 origin of this disease, which he considered as a kind of fungus, 

 arising in the alburnum, from an obstruction of the vessels, 

 and bursting through the bark, which became involved in the 

 disease. These tumors appear to me to begin between the 

 bark and wood. They are at first soft, cellular, and full of 

 sap, but finally become hard and woody. But whether 

 caused by vitiated sap, as Dr. Burnett supposed, or by the 

 irritating punctures of insects, which is the prevailing opin- 

 ion, or whatever be their origin and seat, they form an 

 appropriate bed for the growth of numerous little parasitical 

 plants or fungi, to which botanists give the name of Sphceria 

 mwbosa. These plants are the minute black granules that 

 cover the surface of the wart, and give to it its black color. 

 When fully matured, they are filled with a gelatinous fluid, 

 and have a little pit or depression on their summit. They 

 come to their growth, discharge their volatile seed, and die 

 in the course of a single summer ; and with them perishes 



