K.—BOTANY 171 
establishment of ‘ Mildew’ in wheat, or ‘ Black Rust’ as it is now called. 
For instance, Marshall writing in 1781 in The Rural Economy of Norfolk 
says ‘the idea that the barberry plant has a pernicious quality (or 
rather a mysterious power) of blighting wheat which grows near it, whether 
the idea be erroneous or founded on fact, is nowhere more strongly rooted 
than among the Norfolk farmers.’ Fundamentally, plant pathology is a 
branch of botany, and I hope that the tradition which has grown up in 
this country of training plant pathologists first to be all-round botanists 
will always be maintained. Later on, of course, they should become 
familiar with the practices and economics of crop production, but unless 
they have been inculcated with an adequate knowledge of botanical 
principles and are well acquainted with botanical technique they will 
always be handicapped as investigators of the problems of disease in plants. 
Mycologists and plant pathologists have frequently been the scientific 
pioneers in the development of the extensive Departments of Agriculture 
which are now universally present in tropical countries. ‘Tropical agri- 
culture is often chiefly applied botany, for it is usually much more con- 
cerned with plant than with animal production. The first problems of 
crop production in the tropics which clamoured for attention were those 
of epidemic disease, and the early mycological investigations shewed that 
it was just as essential for crop plants to be studied by scientific experts in 
the tropics as in temperate countries. Credit is due to these mycological 
pioneers for the confidence they won as to the merits of the application of 
science to the improvement of crop production in the tropics. Nowadays, 
of course, botanists of many kinds are employed in the tropical Depart- 
ments of Agriculture. 
Some notable advances have been made in recent years in the control of 
plant diseases. First and foremost, the discovery by Biffen 1 that suscep- 
tibility and resistance of wheat varieties to Yellow Rust (Puccinia glumarum) 
were inherited in Mendelian fashion gave a great impetus to plant breeders, 
often working in association with plant pathologists, to synthesise new 
varieties of crop plants which would be resistant to specific diseases and 
which at the same time would retain the valuable commercial qualities of 
the older varieties. In addition, selections of resistant forms from amongst 
mixed populations and the independent propagation of these resistant 
types have also led to marked improvement in crop production through 
reduction of disease. Such genetical and selection methods have led to 
great advances in the control of certain wilt diseases, Black Rust of wheat 
in North America, and the serious leaf-curl virus disease of cotton in the 
Sudan. The skill of the geneticist indeed may be the only hope for the 
maintenance of certain kinds of cultivated plants as, for example, Antir- 
rhinums, which were devastated in this country last summer by Puccinia 
Antirrhini. Direct control of this Rust appears to be impossible at present, 
and until new resistant races of this popular plant have been built up 
the outlook for its continued cultivation in this country is a dismal one. 
Fortunately, some progress in this respect has already been made in the 
United States. It is sometimes claimed that the work of the plant pathologist 
will pass wholly into the hands of the plant breeder in the course of time. 
1 Jour. Agric. Sci., 2, p. tog (1907). 
