32 THE SCOTTISH BOTANICAL REVIEW 
would have been great if she had not had an organised department 
to arrest and quarantine these infected plants even at the eleventh 
hour. 
The Weymouth pine is a very desirable tree to grow, not only 
arboriculturally for ornamental purposes, but also sylviculturally for 
the sake of its timber. It is called White pine in America, but on 
this side of the Atlantic its timber is known as Yellow pine, a kind 
of timber which has become very scarce and expensive of late years, 
owing to its having been too severely exploited in America. I have 
seen this tree growing well in the South of England, where it gave 
every promise of forming an excellent stand of timber in a compara- 
tively short rotation, but I also noticed traces of this disease in its 
neighbourhood. In Scotland the Weymouth pine grows quite well 
in suitable places, but the disease is unfortunately rampantly 
epidemic. 
The fungus belongs to the group of metoxenous forms, its alter- 
native host being almost every species of Ribes—certainly 7. nigrum, 
R. alpinum, R. aureum, and R. grossularia. This fungus is doubly 
injurious, since it attacks two host plants of economic importance. 
No effort should therefore be spared to prevent the further spread 
of this disease or to stamp it out, and such is not beyond the power 
of properly organised practical mycology. "The remedy recommended 
is to remove whichever of the host plants is considered to be of the 
least economic value. 
There exist among cultivated plants different varieties, some of 
them predisposed to disease, others immune. The immunity may 
be due to anatomical or physiological differences. Whatever the 
cause of the immunity may be, we can always test whether it exists 
or not by experimental methods. The fact of great importance is 
that it is possible to produce varieties which can resist certain 
diseases, and we are now learning more about the laws which govern 
the production of varieties, so that the special variety desired can be 
produced with greater certainty and rapidity than was formerly the 
case. Our future efforts in stamping out disease must be concentrated 
more on the rearing of resistant varieties than has been the case in 
the past, and this is another of the ways in which the modern science 
of Genetics will prove of great value in applied botany. 
The remedies for plant disease are mostly all of the nature of 
antiseptics or fungicides. They are not of the nature of medicines, 
as generally understood in animal ailments. Still, much may be 
done by keeping the plant healthy, and supplying it with the right 
kind and amount of food. Attention to the proper supply of water, 
heat, and light is also of importance. In other words, keep the 
plant in a proper hygienic condition, and it will, like the animal 
under similar conditions, be better able to resist all kinds of disease. 
In order to do this we must study and understand the inter-relation- 
ship between the plant and its surroundings, and it is in this 
connection that the study of plant cecology from a physiological 
point of view is of such vital importance. 
