DISEASES OF PLANTS: 353 
fusty. Insects sometimes bring on an exulcera- 
tion, and other unknown causes likewise produce 
it spontaneously: No: ulcer heals up by itself in 
plants, and it will do more or less harm, and even 
prove fatal, the slower we are in giving proper as- 
sistance. All ulcerated parts ought to be taken off, 
and the sound parts covered with a coating of graft- 
ing wax, or of Forsyth’s cement. Anulcer often 
corrodes wood, pith, or other parts of trees, from a 
neglect of the gardener ; in this case all that is atfect- 
ed, must immediately be cut away, and as just now 
mentioned, the access of air must be prevented by the 
application of some grafting wax or cement. 
From unknown causes the bulbs of hyacinths and: 
other fleshy roots exulcerate: ‘Those too must. be 
healed by putting them in a dry place, taking off 
the diseased part, and covering it with cement. 
However, we rarely succeed, as the bulbs are mostly 
corroded to the very centre*. 
§ 328: 
* The best external remedy for plants is the grafting wax, 
it carefully prepared. In many cases, however, especially for 
large wounds, Forsyth’s cement, for the receipt of which the 
king of England payed 3000l: is by far preferable to the for- 
mer. ‘This last consists of 16 parts of cow dung, 8 parts of 
dry lime taken ftom an old. building, as much charcoal, and 
ene part of sand out of a river, which are to be mixed to- 
gether into a thick mass In place of the cow-dung, ox’s 
blood, .and instead of the lime, dry carbonat of lime may be 
employed: . his cement is-to be spread thinly on the affected 
part, and to be rubbed with a powder, consisting of 6 parts 
of charcoal, and one part of the ashes of burnt bones or car- 
| bonate 
j 
Zé. 
oF 
