New Yorx AGRICULTURAL EXPERIMENT Station. 347 
fruit. The decay progresses rapidly in the ripe fruit; in some 
instances the greater portion of the surface became brown, and 
mature spores of the fungus were formed in six days. 
In the spring of 1899 a Sphaeropsis was found on dead and 
dying Japanese plum trees at Riverhead, N. Y. Cultures were 
made of the fungus, and apple, pear, and quince fruits were 
inoculated. Black rot was again produced in the inoculated fruit 
while the check fruits remained sound. 
These results led to an investigation of the local distribution of 
the genus Sphacropsis, when it was found to be widely distributed ; 
as the list of host plants given in Tables I and II will show. 
Cultures were made of the Sphaeropses from each host and apple, 
pear, and quince fruits were inoculated with cultures from each so 
far as the supply of fruit would permit. Three fruits at least, and 
in a majority of instances six, were inoculated with cultures from 
each host. ‘Black rot was readily produced in the fruits, there 
being apparently no difference in the effect of the Sphaeropses as 
obtained from the different hosts. The inoculated fruits as well 
as the checks were kept in closed glass pars, as before. 
During the progress of the work it was noticed that in most 
cases there was but little difference in the average size of the 
spores as they occurred on the different hosts. It was also found 
that when apple, pear, or quince fruits were inoculated with 
cultures of Sphaeropsis from these hosts the resulting spores were 
larger and of the size of those found on fruits attacked by black 
rot. The series of spore measurements given in the table below 
was made to show the relation of the average size of the spores 
to the host on which they are grown. Since spores of Sphaeropsis 
as they occur on any host vary greatly in size, even in the same 
pycnidium, an average of fifty measurements was taken in each 
instance. 
Table I gives: (1) A list of hosts from which cultures of 
Sphaeropsis were made; (2) average length of 50 spores as they 
occur on the hosts; (3) average length of 50 spores as they occur 
