Peziza Willkommii, R.H., on Larix occidentalis, 
Nutt., and Larix leptolepis, Gord. 
BY 
A. W. BORTHWICK, D-Sc., 
LECTURER ON ForEST BoTANY, UNIVERSITY OF EDINBURGH. 
With Plate LV. 
THE principal aim in sylviculture, as well as in the sister 
sciences of horticulture and agriculture, is not merely to grow | 
plants, but rather to direct their development in such a way that 
they will produce the most useful material. This necessitates a 
certain amount of interference with the plant’s natural course 
of development and habit of life. It is not always possible to 
avoid placing the plants in somewhat unnatural positions, and, 
again, a large number of individuals of the same species are 
frequently grown in close proximity to each other. Cultivated 
plants are thus not under the same conditions as those which 
grow naturally. The less we interfere with nature and allow 
the plants to grow under as natural conditions as artificial 
cultivation will permit, the better will be the results. This is 
a fact of great importance, especially in sylviculture, where the 
trees require a long period in which to complete their develop- 
ment. 
In horticulture and agriculture the case is slightly different. 
Here the plants are not so long lived, and consequently not 
exposed to such a prolonged strain. Under cultivation, plants 
tend to become less resistant in regard to their natural enemies 
in the shape of insects and fungi. Consequently they are more 
liable to be affected by epidemic diseases which may cause 
large pecuniary loss not only to the cultivator, but to the country 
at large. ‘: 
Plant pathology is concerned with the disease of plants just 
as medicine and veterinary science is concerned with the cure 
of disease of man and animals. The plant pathologist’s scope 
is, however, more limited. Individual attention cannot be 
given to each plant in a forest, and consequently the method 
by which success is most likely to be attained is that of pre- 
[Notes R.B.G., Edin., No. XXI, August 1909.] 
