C. H. PECK ON THE " BLACK KXOT." 83 



iUic exesvm foramen, forte e frofvndo progressa^y At a later 

 day, in writing n})on this same subject in Lis SynojDsis of North 

 American Fungi, he says : " Pavcis cinnis post, fere omnes clesfrvQti 

 sunt, comhinato furore hvjvs fmigi et Ct/nifisy And again he says : 

 " JEt in Jus omnibus Cynipis fungnsqve incepiunt scevire^ Thus he 

 constantly associates the insect which he calls Cynips with the 

 fungus, without definitely assigning the honour or dishonour of the 

 mischief to either. We find the following in Harris''s Treatise on 

 Injurious Insects : " 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 colour. Professor Peck 

 referred tbis disease, as well as that of the cherry tree, to the 

 agency of insects. Dr. Burnet rejected the idea of the insect 

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

 * * * But whether caused by vitiated sap, as Dr. Burnet sup- 

 posed, or by the irritating punctures of insects, which is the pre- 

 yailing opinion, they form an appropriate bed for the growth of 

 numerous little parasitical plants or fungi." 



Dr. Fitch claims to have made a careful investigation of this 

 subject, and as his observations are quite accurate we again quote 

 from his address : " There has been much speculation as to the 

 cause and true nature of these excrescences. * * Most persons 

 suppose them to be of insect origin. The larvee of the curculio 

 are almost always found in them, and these larvae consume nearly 

 all the spongy matter of the warts, but do not touch the little 

 fungus growing on their surface, which remains, forming a kind of 

 shell, after the whole inside is devoured. But as these excrescences 

 are sometimes found wholly free from curculio larvae and all other 

 worms, it is obvious they are not the cause of their growth. * * 

 Suffice it to say that now, having carefully examined these excre- 

 scences from their commencement onward through their subsequent 

 growth, I am prepared to say, with the fullest confidence, that the 

 microscope shows nothing whatever about them, externally or in- 

 ternally, indicating that an insect has anything to do with causing 

 them." Then, after giving his views as to what constitutes a fun- 

 gus, he says : " We arrive at the conclusion that these excrescences 

 are not of insect origin, and are not a vegetable fungus, but are 

 properly a disease of these trees, in many respects analagous to the 

 cancer in the human body." 



Mr. Walsh, whose definition of black knot we have already 



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