358 | [ ASSEMBLY 
varieties conveniently situated for observation, together with a nearl 
entire absence of spontaneous outbreak of the disease in the immed- 
iate vicinity; the only occurrence of blight on the Station farm not 
produced by inoculation being upon a few twigs on one of the quince 
trees. These were discovered July 26, and promptly removed. A 
branch or two blighted on a pear tree half a mile distant, and were 
removed July 11, but so far as known no other cases occurred 
nearer the Experimental orchard than a mile and a half. A total of 
one hundred and twenty one inoculations were made. In the first 
seventeen experiments, all made the same day, the inoculation was 
performed by removing a small amount of the sticky exudation from 
a freshly blighted pear branch and inserting it in the tissue to be © 
infected by using the point of a pin. In all subsequent trials some 
of the deseased branch was sliced into enough water to barely cover, 
rinsed about for a few moments, and removed, which left the water 
slightly milky. The inoculation was made by puncturing the tissue 
of the plant with a pin and applying a drop of the infusion. The 
use of the exudation is troublesome, as it is often inconvenient to 
procure it in good condition and owing to its adhesiveness is inserted 
in the wound with difficulty. The infusion conveys the infection 
with equal certainty. These inoculations were performed late in the 
afternoon, and when convenient on a damp day, but no other pre- 
cautions were taken to insure a perfect inoculation. 
.The accompanying tables give each experiment by number (ex- - 
periments of all sorts being numbered consecutively as undertaken), 
the part of the tree which was inoculated, the source of the virus 
used in the inoculation, and the number of days intervening between 
the time of inoculation and the first external indication that the 
disease had taken hold of the healthy tissues. 
A glance at these tables shows so plainly that the disease may be > 
Prar. 
No. of Part Source Days of 
experiment. treated. of virus. incubation. 
A NSEN oti hE Ta ee Stem. Pear. 8 
ROU eretan tates stir ae eta hier 2 8 
gOS Lie geeks IS BE eee pee AS Bre sa BoB © 43 6 
QO? SUES Ratna sleet e Go's tall seared is s 6 
Bla ec ee PEER senca Weta vat erahel sais F - 9 
DE ee AE Gl er eka Crate _ 9 
LAR SNE adr, thd a crate ate gee fe s 
Sb AE Teh eRe UPROMISE lds) Ab cr Ss - 
DO Si Yin NEU Ala loo (eth se Seeded < 2 10? 
Dab) ARLE Maoh 9 DIN Wises forse ! aa zs 
OD Sv, cael rie s]e eles Sine vin Serene “ Apple. 23 
ar Sn PER PEP Ge ee pA FAH TES : Eo 9 
