1896.] The Bacterial Diseases of Plants: 923 
particular. “In 1883 innumerable were the cases in which I 
observed that the descending stripe on the leaves was dried out 
and stopped, so that the bulb was not attacked.” The rapidity 
of the infection depends largely on the temperature, the damp- 
ness in the surrounding air,and on the amount of water in the 
plant itself. The location of the wound might also make a 
difference. 
(4) Methods of Prevention—An inquiry among the growers 
elicited the statement that there is a great difference in sus- 
ceptibility. This Dr. W. thinks cannot be denied. Some 
varieties are very subject; others, in the same beds or gardens, 
have not been known to be attacked. Many varieties formerly 
held to be exempt from the disease are now known to be sub- 
ject ; but some remain which have never yet shown the yellow 
disease, and this cannot be ascribed to mere accident; on the 
contrary, it can be explained only by assuming that predisposi- 
tion or readiness to be attacked here plays a prominent part 
(Verslag, 1883). Anatomically, so far as known, all are alike. 
Lists of “very susceptible,” “less susceptible” and “not sus- 
ceptible ” varieties are given, from which it would appear that 
single varieties are more susceptible than double ones, and the 
exemption of the latter is not due to their lesser number. All 
of the double red varieties and most of the other double sorts 
are exempt, or but little subject to attack. These lists are based 
on statements furnished by only seven growers, but include 
many varieties (Verslag, 1885). Of thirteen varieties said 
to be very susceptible by several or most of these seven growers 
only one is double, la Tour d'Auvergne, On this account, differ- 
ence in recepti vity is suggested as a means of combatting the dis- 
ease. New t not be originated from ones 
Seedlings should be derived from “hardy sorts, and by artificial 
fecundation, the pollen of susceptible varieties being excluded. 
Otherwise, through the agency of insects, the resulting cross 
may prove susceptible. The law of heredity is shown still 
more rigorously in non-sexual reproduction. It is best, there- 
fore, to discard sensitive sorts and try to obtain new ones 
which are more robust. 
In the division of bulbs for propagation the pet s care 
should be taken never to cuta healthy bulb with a knife which 
