Siiggestlojis lo prevoil i/s appearance. 289 



form and size, are these galls, compared with these excres- 

 cences, which are very irregular in form and size. 



Ho far as I have been able to observe, by dissecting these 

 fnngi, they appear to arise in that part or texture called the 

 Alburnum. 



I have thought that the proximate cause might be, an 

 obstruction in the vessels of that texture, by reason of the 

 unhealthiness of the sap. The vessels burst, and the sap 

 is poured out under the bark. Now the sap is as full of 

 the life of the tree as blood is full of the life of an ani- 

 mal. 



This extra vasated sap will immediately become organ- 

 ized, or partially so, and, rapidly increasing, burst through 

 the outer bark and make its appearance. 



This fungus is not confined to the young wood, but is 

 produced upon limbs of large size, the outer bark of which 

 the Curculio would not be able to puncture. 



It makes its appearance from June up to August. These 

 fungi come in all forms ; sometimes in a single spot, and 

 then again extend along the limb for several inches, always 

 with an irregular granulated surface. This want of uni- 

 formity in form, size and location, is evidence that it is not 

 caused by an insect. After being cut from the large limbs, 

 these fungi will often sprout out again between the wood 

 and the bark where the wound is made, and require a sec- 

 ond operation. 



Now, this would not be the case if caused by an insect. 

 This disease may often be noticed under the bark before it 

 burst, upon large limbs, where the bark is strong, which, 

 if slightly opened with a khife, will yield to the pressure, 

 and the fungus soon appears. 



While this fungus is young and tender, the Curculio finds 

 it a convenient receptacle for his eggs, the juice of which 

 affords abundant nutriment for the larvae. A pretty sure 

 sign, by which you may know that he has used it for that 

 purpose, is a small drop of gum oozing from its surface; 

 and where you do not see this sign, you may not expect to 

 find his larva within. 



I have said that this disease begins in the part called the 

 alburnum. This is the texture through which the sap 

 ascends ; but it soon involves every texture of the tree — 

 wood and bark — and is malignant and surely fatal to the 

 limb on which it grows. It is as destructive to the tree as 



VOL. IX. NO. VIII. 37 



