BULLETIN OF THE BUSSEY INSTITUTION. 447 
and, on the other hand, the knot tends to increase the number of cur- 
culios, by offering a suitable place for the deposit of their eggs. As a 
rule, the trees once attacked by the knot grow more and more diseased, 
both by the extension downwards and upwards on the stem of the old 
knots, and by the production of new ones from the germination and 
growth of spores of the old knots on other branches which have 
been previously free from them. More and more of the smaller branches 
are killed by the girdling effect. of the knots; and the nutrition of the 
larger branches is evidently so decidedly impaired, that to bear fruit is 
entirely out of the question ; and, after lingering in a diseased condition 
for a few years, the trees themselves die. We cannot say certainly for 
how many years a given knot may continue to elongate; because the 
older parts crumble, and leave no distinct mark by which the annual 
growth may be traced. One can, however, often recognize knots 
which have been growing for at least three years. In a few cases the 
branches seem able to recover from the knots, and the scars which 
indicate the previous seat of the disease can be seen. 
The fungus causing the knot was first described by Schweinitz, in his 
“ Synopsis Fungorum Carolin Superioris,” under the name of Spheria 
morbosa, in the following words: “S. cespitosa astoma maxima recep- 
taculo bullato fusco, sphzrulis minoribus irregularibus albofarctis.” 
At the time Schweinitz wrote, nothing was known of secondary forms 
of fruit in the Spheria. The conidia were first described by Mr. C. 
H. Peck, in a paper on Botany, read as a report before the Albany 
Institute, February 6, 1872. He describes the conidial spores as “ at 
first simple, but soon becoming one or more septate.” We have never 
seen them other than ‘simple; but, judging from other Cladosporioid 
conidia, we should expect the spores to divide at some time.’ Since 
Schweinitz’s day, the genus Spheria has been more or less cut up by 
writers into different genera; and the question naturally occurs, To 
which of them shall we refer Schweinitz’s Spheria morbosa? Curtis, 
in his Catalogue of Plants of North Carolina, still calls it a Spheria ; 
and places it in the division Hrumpentes, subdivision Cespitose, 
between S. nobilis, B. & C., and S. Perisporioides, B. & C., to which, 
more particularly the latter, it bears but little resemblance. Mr. C. B. 
Plowright, in “Some Remarks upon Spheria Morbosa,” in the “ Monthly 
Microscopical Journal” for May, 1875, thinks it should be placed in 
