362 [ ASSEMBLY 
riety, the age of the fruit, and several other factors may have had 
some influence, but the season’s work seems to show that these are 
subordinate. Three Bartlett pears inoculated August 2 (exper. 
118 to 120) gave very slight exudation, and three pears of each of 
the following varieties, Bartlett, Howell, Flemish Beauty. Mt. 
Vernon, Seckle and Doyenne Bussac, inoculated August 9 (exper 
148 to 162, not tabulated), gave no exudation whatever. In these 
cases there appeared to be no doubt that the lack of exudation was 
due toa milder form of the disease induced by the approaching 
ripeness of the fruit, for in each case the pears became quite mellow 
before the.experiments were closed. The last named experiments 
were undertaken to see if any difference could be traced in the action 
of the disease in the several varieties used, but owing to the lateness 
of the season, or rather ripeness of the fruit, no conclusions could be 
drawn. What is true of the fruit in regard to succulency, is ap- 
parently true of the other portions of the tree, but of necessity in a 
less marked degree. It may be that the supposed susceptibility of 
certain varieties is in part referable to their possessing softer tissues 
or lateness in maturing the recently formed parts. But it is a ques- 
tion requiring more data than isat hand and must be left for further 
study. 
Macaiher point made by Professor Burrill was that the blights of pear, 
apple and quince are identical, a conclusion that my own work fully 
sustains, for in all the experiments performed the result did not in 
-any way appear to be influenced by the source of the virus. That. 
made use of was from apple, pear and quince, mostly obtained from 
young nursery trees about a mile and a half away. As shown in the 
tables, it was used both upon the same kind of trees from which de- 
rived and interchangeably, and as I have said without appreciable 
difference in the results. The test was carried even a step further by 
using a virus from quince, which had received its infection from 
pear, aud continuing the disease in the pear, apple, quince, ete. Several 
such permutations were made with no variation that could be traced 
to the changes. 
If the disease would thrive upon the apple, pear and quince, it 
seemed worth while to test its action upon other plants. Eight in- 
oculations were made upon June-berry (Amelanchier Canadensis) of 
which two were thoroughly successful. These two were on tender 
growing shoots with immature leaves; those that failed were in shoots 
of the present season’s growth but fullsize and fairly ripened. Ido not 
therefore doubt that the maturity of the shoots was quite sufiicient 
to account for the failures. Nine experiments were tried upon thorns, 
two being upon the English hawthorn (Orataegus Oxyacantha), and 
the remainder upon the evergreen thorn (Crataegus Pyracantha). Of 
the two instances on hawthorn (exper. 91 and 92) one resulted 
in completely killing some inches of the shoot, while the other ex- 
tended less than an inch along the stem but then stopped, and as it 
did not encircle the stem, the shoot was not killed. Of the instances 
