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THE PRACTICAL ENTOMOLOGIST. 



view it would appear to do. Towards the middle 

 of August, the new Black-knot, having perfected 

 its seed, gradually dries up and becomes internally 

 of a reddish-brown color. In other words, like so 

 many other annual plants, it dies shortly after it 

 has perfected its seed, just as a stalk of wheat or of 

 corn dies shortly after the grain is ripe. 



'2ni1. During the months of June and July I col- 

 lected from time to time very numerous specimens of 

 Black-knot, some of which I cut into to see what 

 larvae they contained, and some I preserved to see 

 what perfect insects could be bred from them. 

 Besides seven specimens of the common " Curculio," 

 which many persons had previously bred from 

 Black-knot, I bred for the first time therefrom no 

 less than five distinct species of insects,* none of 

 which can be considered as gall-makers, but not a 

 single true gall-maker; and I can confirm Dr. Fitch's 

 assertion, that some specimens are wholly free from 

 larvae of any kind when cut into. 



We will now take up in order the three diflferent 

 theories respecting the nature and origin of Black- 

 knot, which, as already stated, have been maintained 

 by different writers. 



\st. That Black-knot is a mere disease like the 

 cancer. — Dr. Fitch, who maintains this opinion, 

 allows that the black granules found on the Black- 

 knot are a true fungus, " that the surface of these 

 excrescences, when mature, is always covered with 

 this plant," and tnat " this plant never grows, or at 

 least has never been found, in any other situation." 

 {Address N. T. State Agr. Soc. 1860, p. 21.) 

 Yet, in support of his peculiar opinion, he argues 

 as follows : — " What is a fungus ? To express it in 

 familiar language, it is a body which grows and 

 forms its own substance, distinct from and inde- 

 pendent of the body in which it takes root and from 

 which it draws its sustenance. Now these Black- 

 knots are not such a growth. They are merely a 

 change in the texture of the natural parts of the 



♦July 21, Ceratopogon — (determined by Osten Sacken.) — 

 Aug. 23, Cecidomyia {diplosis) se^/e7ft-mac»/rt^a Walsh, {also 

 inquilinous in a Willow-gall.) — Aug. 25 — Sept. 27, three 

 distinct new species of Sedya? (Microlepidoptera) ex- 

 panding .35 — .40 inch. — July 22 — Sept. 24, Conotrachelus 

 nenuphar ("Curculio.") I strongly suspact that Stya/phu^ 

 eurculionis Fitch is parasitic, not as Dr. Fitch supposes 

 upon the " Curculio," but upon some of the minute moths 

 that inhabit the Black-knot, because I have bred other 

 Cryptogastrous Ichneumon-flies from Willow-galls, in 

 which small moths, including two distinct new species of 

 Hedya described by Dr. Clemens, are very commonly in- 

 quilinous, and the authors of which, being Cecidomyia, 

 oould not have been infested by an Ichneumon-fly. For, 

 BO far as my experience extends, Cecidomyia is infested 

 only by Chalcididce and Proctotrupid/x. 



limb." {Ibid. p. 22.) According to this defini- 

 tion of the term " fungus," what is commonly called 

 "mould" in a loaf of stale bread is not a fungus, 

 because it is not "distinct from and independent of 

 the body in which it takes root;" and on the other 

 hand, an apple or a peach must be a true fungus, 

 because it is " distinct from and independent of" 

 the apple-tree or the peach-tree. But leaving the 

 Botanists to settle the validity of this definition, 

 surely if, as Dr. Fitch concedes, the Black-knot and 

 the fungus are always found in company and never 

 by themselves, the one must be part and parcel of 

 the other; otherwise we might naturally expect, if 

 not to find the fungus without the Black-knot, at 

 all events to find occasionally the Black-knot with- 

 out the fungus. In reality a Black-knot is an as- 

 semblage of funguses, just as a tree is an assemblage 

 of buds; and just as each Black-knot fungus is a 

 distinct individual, so many Botanists are of opinion 

 that each bud in a tree is a distinct individual, the 

 tree itself being merely the stock upon which the 

 individual buds grow, as the Black-knot is the stock 

 upon which the individual funguses grow. 



2nd. That Black-knot is a gall. — As already 

 stated, there is no true gall-making insect that in- 

 habits the Black-knot, so far as I can discover on 

 the fullest and most extensive investigation that I 

 have been able to give to the subject. The minute 

 holes, commonly found in the old dry Black-knot, 

 which are too large either for the "Curculio" or 

 for the small moths bred by myself from Black-knot, 

 are of a suitable size for either of the two Dipterous 

 insects which I have enumerated in a note as bred 

 by myself from Black-knot. Consequently the ar- 

 gument which I based upon the existence of these 

 minute holes {Free. Ent. Soc. Phil. III. p. 614) falls 

 to the ground ; and although I found on one occa- 

 sion the larva of a Gall-gnat embedded in a cell in 

 a Black-knot, yet this was most probably that of the 

 Guest Gall-gnat which I actually bred from Black- 

 knot, as stated in the note, and not of a true gall- 

 making Gall-gnat. 



Srd. That Black-knot is a fungus. — Just as Dr. 

 Fitch, having proved to his own satisfaction that 

 Black-knot is neither a gall nor a fungus, infers by 

 the method of exhaustion that it must be a disease; 

 so, having proved that it is neither a di.sease nor a 

 gall, we may infer by the method of exhaustion that 

 it must be a fungus, or rather an assemblage of fun- 

 guses. In confirmation of this theory may be ad- 

 duced the very remarkable analogies, between the 

 structure of the Black-knot and that of the fungus 

 described above as occurring on Red Cedar. That 



