THE ANATOMY AND OTHER FEATURES OF THE " BLACK KNOT" II3 
supposedly difficult technique involved in preparing proper sections 
for study. 
About the first paper to appear which deals in any way with these 
points was that of Peck (6). In a communication read before the 
Albany Institute this author discusses in a general way, among other 
subjects, the external morphology of the knot, the structure of the 
conidia, the time of ripening of the ascopores, methods of control, 
etc. The next paper to appear on this subject was by Farlow (3), 
in which the life history of the fungus is described in detail. The 
histology of the knot is also discussed rather fully and the results 
given have been largely copied by all of the subsequent writers on 
this subject. It is evident from the figures that only later stages in 
the development of the knot were studied in the preparation of this 
paper. Crozier (i) speaks briefly of the structure and time of ripening 
of the ascospores. He also mentions the fact that when the knots 
are young the distinction between bark and wood still exists, the 
cambium line being deflected outward through the knot, a statement 
which seems to have been overlooked by subsequent writers. Humph- 
rey (4) describes some interesting results obtained from germinating 
and growing spores on culture media, stages in the life history of the 
fungus, and some of the structural characters of the knot. Lodeman 
(5) offers suggestions as to how the fungus gains entrance to the 
tissues of the host, and deals with the disease in an economic way. 
So far as I have been able to learn the above cited papers are all that 
offer anything new concerning the anatomy of the knot or of the 
morphology of the fungus. 
The choke cherry, Prunus virginiana L., grows very abundantly 
in the vicinity of Durham. Thickets of these bushes occur along 
roadsides and waste places which are usually badly infected with the 
black knot fungus. I found, however, that this was the only species 
of cherry that was infected in that vicinity as both the pin cherry, 
P. pennsylvanica L., and the wild black cherry, P. serotina Ehrh., grow 
there, but in no instance was either of these species found to be in- 
fected. In one place near Durham pin and choke cherries grow so 
close together that their branches intermingle, but in no instance were 
the branches of the pin cherry infected, although those of the choke 
cherry were covered with knots. Thickets of choke cherry bushes 
grow all around the agricultural college farm at Durham, but in 
pruning the orchard of cultivated plums, during the year that I was 
