REPOKT OF THE BOTANIST. 175 



Third. That j\Ir. Mclvor's j>iau of mossing the bark is au important 

 discovery in the direction of int^'lligent culture. 



Fourth. That the place of deposit of the alkaloids is in the cellular 

 tissue of the bark, beginning* from the cambium outward. 



Fifth. That the sources -whence the materials are drawn for this elab- 

 oration are at once the nourishing sap descending* in its usual course, 

 and a lateral conveijancc through the rncdnllarr/ rays of j)art of the deposit 

 of the mother substance in the wood. 



Sixth. That the chlorophyllion respiration does not favor, but that the 

 general respiration does favor, the pi'oduction 0/ alkaloids. 



Seventh. That the laticiferous ducts dwindle and disai)pear coiuci- 

 dentall^- with the formation of alkaloids. 



THE-BLACK KNOT OF PLUM AND CHEERY TREES. 



The following extracts are from a paper by Professor C. H. Peck, of 

 Albany, New York. The importance of the subject, and the clear and 

 thorough investigation which Professor Peck has given it^are sufficient 

 argument for its introduction : 



Attention has been given for some time past, by one of your committee, to the investi- 

 gation of the canse and natnro of the so-called black-lcnot, that terrible pest of the plum- 

 trees and cherry-trees of our country. Various and contiicting opinions have been 

 entertained respecting its character, but all agree in pronouncing it a very injurious 

 and even fatal visitant to the trees it afiects, and all ^vho have proposed any remedy, 

 so far as Ave are aware, have recommended the most thorough use of the knife. 



It is a noticeable fact that most of the authors vs-ho have written upon this subject, 

 wrote as entomologists, not as botanists, and any errors they may have falleu into 

 should, therefore, bo looked upon with leniency. One author even apologizes to the 

 botanists for " stealing their thunder," as he exiiresses it, pleading as his excuse that 

 ho had at first mistaken the black-knot for an insect gall. We think the botanists 

 scarcely deserve an apology, since they have so persistently neglected to investigate 

 a matter of so much importance. 



What is t)lack-knot ? To this question Dr. Fitch, entomologist of the Now York 

 State Agricultural Society, answers : " It is a large, irregular, black, wart-like oxcres- 

 cence which grows upon the limbs of plum and cherry trees, causing the death of all 

 the branch above it, and extending down the limb farther and farther every year till 

 the whole branch is destroyed, other limbs at the same time becoming alfected in the 

 same manner, and also the limbs of other trees in the vicinity. If it is neglected it in 

 a few years kills the tree." 



The late lamented B. D. Walsh, entomologist of the State of lUiuois, thus defines it: 

 " It is a black, pntfy, irregular swelling on the twigs and smaller limbs of plum and 

 cherry trees, and, in one instance that came under my observation, of peach-trees, 

 making its first appearance in the latitude of New York early in June, and attaining 

 its full growth by the end of July. Usually a tree that is attacked in this manner is 

 atiected worse and Avorse every year until it is finally killed, and, where one tree of a 

 group is alFected, the malady usually spreads to them all in process of time." 



According to our observations the death of the branch above the excrescence is not 

 always produced by the first attack. In such cases the malady extends upward as 

 well as downward. The time of the first appearance of the excrescence is in late au- 

 tumn, althougli the external development of the fungus is not manifest until the fol- 

 lowing May. We have never found it on peach-trees. 



Let us now see what is written concerning the origin of black-knot. Schweiuitz, the 

 botanist, who wrote the original description of Sjyhccria moriosa, the fungus that de- 

 velops itself on the excrescence, seems to have been in some doubt concerning the origin 

 of the tumor. In his description ho uses these words : ^^ Raec massa ninii sit effcclns 

 ictiium Cijnijyis vcscimiis, videmus tamcn hie iniccxesian foramen, forlr e prof undo progtisw." 

 At a later ttay, in writing upon this same subject in his Synopsis gf North American 

 Fungi, he says : " Panels annis x>ost, fere omnes dcsinicii sunt, comhinato furore hujus fungi 

 et Cynijjis.'' And again he says : " Et in his o^nnihus Cynijyis fnngusque incejnunt savire." 

 Thus ho constantly associates the insects which he calls cynips with the fungus, 

 without definitely assigning the honor or dishonor of the mischief to either. We find 

 the following in Harris's Treatise on Injurioiis 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 color. Professor Peck referred this disease, as well as 

 that of the cherry-tree, to the agency of inss-cts. Doctor Burnet rejected the idea of tho 



