378 



NEW ENGLAND FARMER. 



Aug. 



before frost ; whereas, when not shortened in, the 

 beans on the upper ends of the vine cannot per- 

 fect themselves in time to be saved. It is unfair 

 to expect a gill of sap to travel through forty feet 

 of vine wrapped around a pole, and make a perfect 

 bean at the extreme end of it. 



BLACK KNOT IN PLUM TREES. 



Mr. Editor : — When the carrier brought the 

 last Farmer into uij door-yard, I met him, as I 

 was returning from my garden, where I had been 

 carefully examining some of the newly forming 

 "knots'* upon some young sprouts growing, or 

 trying to grow in the vicinity of an old "purple 

 damson" tree. I took the paper, and the first ar- 

 ticle I noticed, was the one on the first page, call- 

 ing attention once more to this subject. After 

 reading the article, which afforded but little light 

 upon this perplexing point of inquiry, and which 

 was chiefly designed to induce careful observation, 

 at this favorable season of the year, I returned to 

 the garden and renewed my examinations, and I 

 will give you what /arts I have discovered, and my 

 speculations upon them. First the facts. These 

 protuberances, or "knots," commence about the 

 time the leaves open upon the trees, in the charac- 

 ter of a swelling, or enlargement upon the side of 

 the limb, and generally upon wood of the lastyear's 

 growth ; always upon young, fresh and sappy 

 wood. Soon the bark cracks open for considerable 

 extent upon the limb, varying from one to six inch 

 es, and sometimes extending along continuously 

 for half a yai'd. This opening in the bark is rapid- 

 ly filled with a sort of fungus, or porous woody 

 substance, in which the regular fibres of healthy 

 wood do not appear, but which will readily sug- 

 gest to the observer the idea of disease — of a bad 

 sore — of a cancer upon a human limb. Indeed, I 

 can think of nothing they so much resemble as can- 

 cers, or scrofulous sores, I have seen upon the hu- 

 man body. As these sores progress, they extend 

 into the bone, or into the wood, come to the heart 

 of it, and frequently nearly, or quite round and 

 through the entire limb, and the wood becomes 

 porous, resembling a diseased, carious bone, and 

 dies. 



Now for another fact : in examining these pro- 

 tuberances, at this season of the year, I have 

 found, on examining them carefully, near the cen- 

 tral parts of the branches, or more prominent por- 

 tions, a small maggot, very small, but large 

 enough to be seen with the naked eye. My ob- 

 servations this morning, have detected, at least, 

 half a dozen of them, finding one or more in every 

 branch, and often discovering the path, half an 

 inch or more in length, which had undoubtedly 

 been his "path of life," aflbrding him food and 

 shelter thus far in his maggot, or first form of ex- 

 istence. Two or three weeks later than this date, 

 these maggots may be found considerably larger ; 

 but never, I think, attaining to moi-e than three- 

 eighths of an inch in length, and the size of a com- 

 mon pin ; or possibly a little more. Later in the 

 season I have often discovered their path, extend- 

 ing along an inch or more, through the central 

 part of this fungus matter, and leading out at 

 length, where we may suppose he found himself 

 possessed of a pair of wings, and the power of 

 using them. 



Now for my speculations. The inquiry may 



arise, are these fungi, or sores, thrown out as 

 eruptions appear upon the surface of the human 

 body, from disease in the sap, the blood of the 

 tree ? and thus afibrding a convenient place for the 

 moth, or fly, in which to deposit its egg, become 

 incidentally its birth place and cradle ? 



Or does the insect, the moth or fly, in the latter 

 part of the season, insert its egg in the healthy 

 i)ark, or soft wood of the summer's growth, to be 

 hatched out the ensuing season, as the sap flows 

 freely, and the warm sun is felt by it ■? This lat- 

 ter is, I am confident, the true view of the subject. 

 But what is the cause of such an extensive "knot" 

 or sore upon the limb? Certainly no such result 

 follows a slight incision or wound made in the or- 

 dinary way. Is it not probable that N&.ture has 

 prepared this insect, to propogate its kind, through 

 this peculiar process 1 and accordingly by a law 

 we cannot fully scan, made its sting, or the depos- 

 ited egg, act upon the wood as a poison, throwing 

 out just such an excrescence as is necessary to its 

 existence? This is my opinion. And I think the 

 vegetable world affords many examples analogous 

 to this theory. Many a time, in my boyhood, 

 have I plucked a certain forest weed in the pasture, 

 or by the road side, growing perhaps to the height 

 of three feet ; the stock grown, and about as 

 large as a pipe stem, and having, somewhere mid 

 way of it, a ball or bulge, an inch in diameter, and 

 perfectly sound. A careful examination of this 

 ball, showed clearly that some insect had inserted 

 an egg in the stock of the young weed, which 

 caused the fibres to part in the centre, and swell 

 out to the size above described, and containing 

 within a pulpy substance, in the midst of which 

 would be, at first, an egg, and then in due time a 

 maggot, which feeds upon the tender juicy sub- 

 stance, Nature has so wonderfully provided for it. 

 In Autumn these balls will be found to have, in 

 the side of them, a small round hole, through which 

 the imprisoned maggot makes his escape. 



Similar to this are the round balls often seen at- 

 tached to the leaves of the oak, and familiarly 

 called "oak apples." They are composed of veg- 

 etable matter ; their formation is a wonderful 

 specimen of mechanical precision and skill ; and 

 yet they grow, or result from the insertion of the 

 egg of a moth or fly, in the fibrous substance of 

 the young and tender leaf. They form a perfect 

 ball, the wall of which is in substance much like 

 the leaf itself, while in the centre of the large cham- 

 ber within, suspended by fine fibres, extending to 

 the wall all round, is a small sack, or shell, in 

 which at first is an egg, then a maggot, which 

 finally escapes by crawling through the wall of its 

 prison. 



Now in these cases, certainly the hermit insect 

 is the prime cause. She lays her egg, and Nature 

 takes it into its fostering care ; and though we 

 cannot fully comprehend the subtle principles, by 

 which the process is carried on, yet the facts can- 

 not be disputed. Nature, in her beneficence, re- 

 gards not man alone, but all living things. By 

 laws the most subtle, by arrangements the most 

 complete, as they often appear to us, yet really 

 the most free and simple, are the wants of all sup- 

 plied. 



Possibly in some non-essentials in the above 

 theory, I may have erred ; I may not be correct 

 as to the time when the egg is inserted ; when it 

 takes its wings and moves in the air. I have 



