C. H. PECK ON THE " BLACK KNOT." 87 



Having thus dwelt at some length on this subject, we will briefly 

 notice one or two inferences, which we find in the articles of the 

 Practical Entomologist, from which we have quoted. We would 

 not even notice these did we not believe them erroneous and fraught 

 with mischief. It is stated that " about the last of July or the 

 first week in August, there grows from each fungus on the surface 

 of the black knot a little cylindrical filament about one-eighth of 

 an inch long, which no doubt bears the seed or spores, as they are 

 technically termed, of the fungus, and that these filaments very 

 shortly afterwards fall off and disappear, leaving behind them the 

 hemispherical plates, which alone had been hitherto noticed by 

 botanists. * * I discovered that the filaments not only cover 

 the entire surface of the black knot itself, except where a few of 

 them had fallen off, but that they were thinly studded over 

 the twisT for an inch or two above and below the swollen black 

 part." 



We do not pretend to say what these little cylindrical filaments 

 were, not having seen them, but it is very evident, from the fact 

 that they extended on the twig an inch or two above and below the 

 swollen black part, that they had nothing whatever to do with the 

 bearing of the spores of this fungus, for its spores, we have seen, 

 are produced in little sacs within the so-called hemispherical plates, 

 which do not extend beyond the swollen part, and besides, the 

 spores are not mature until long after the assigned time of these 

 filaments. Once only have we observed anything that seems to 

 correspond somewhat with the description of them. In the latter 

 part of August we collected specimens of black knot on the wild 

 bird cherry, Primus i^ennsijlvanica, some of the perithecia of which 

 had a little cylindrical rostrum or beak growing from the apex. 

 But all these perithecia, when cut open, were found to be black 

 inside and entirely barren, while those without the filament or 

 beak even on the same excrescence were white inside, as in the 

 normal condition, and contained rudimentary sacs. We have also 

 frequently seen perithecia without the beak that were black inside. 

 These were, in every instance, sterile. 



We quote once more, this time in reference to the second inference. 

 " But from the evidence which will be adduced below it appears 

 to follow as a necessary consequence, that the black knot on the 

 cherry is caused by a distinct species of fungus fi'om that of the 

 plum." Then the evidence is adduced, which consists iu plum trees 



