8 Prksidext's Address. 



chemist, and the engineer have amongst them solved the problem of 

 the codlin moth : and it only remains for the horticulturist to apply 

 effectually the knowledge which thev have gained, in order to 

 materially reduce, or even to get rid of, the ravages of that pest of 

 our apple orchards. There is promise that the destructive mealie- 

 borer may prove to be controllable by simple means. This problem, 

 as well as the problem of the fruit fly, is now being investigated in 

 the Government laboratory at Grahamstown. And it does not seem 

 too much to hope that before many years have elapsed, the scientific 

 plant-breeder will have succeeded in evolving varieties of wheat and 

 oats which will fully resist rust, whilst proving quite satisfactory 

 in other respects. 



Vast strides in the matter of the study of the hybridisation of 

 plants, and in the selection and fixing of characters of varieties, have 

 been made during the last few years, by the application of new 

 theories of the transmission of characters ; theories which were first 

 formulated more than forty years ago, by Gregor Mendel, to 

 explain the results which he obtained in crossing varieties of the 

 sweet-pea in his monastery garden. Mendel published the result of 

 his work in 1865; but until 1901 it appears to have been completely 

 lost to view. Probably the good Abbot little realised the profound 

 importance of his deductions as regards the realm of practical 

 agriculture. Hybridising used to be described as a game of chance, 

 played between man and plants, in which the chances were in favour 

 of the plants. Mendel's work changed the whole aspect of the 

 problem. His discovery, that in cross-breds the egg-cells and pollen- 

 grains are pure with respect to the characters which they individually 

 carry, explains many facts which were previously mysterious, dis- 

 turbs the foundations of many current theories of heredity, and indi- 

 cates the possibility of picking out the valuable characters from 

 different varieties, and of building up an ideal type within a reason- 

 able time. It is on these lines that, as I understand, the Transvaal 

 plant-pathologist is now working in his endeavours to produce rust- 

 resisting wheats, suitable to South Africa. 



Most of the results which I have mentioned are what may lie 

 called final results; but, valuable as these final results are, they con- 

 vey no clear idea of the amount of strenuous and useful work, lead- 

 ing up to them, which has been done : nor of the work which is 

 still being done, in striving after future results, by many scientific 

 enquirers. The names of the men who have devoted themselves to 

 enquiry into animal diseases, and into plant diseases and pests, will 

 always be gratefully remembered amongst us ; and I should like 

 especially to mention those of David Bruce, of the late Duncan 

 Hutcheon, of Robertson, of Pitchford, of Lounsbury, and last (but 

 by no means least) of Arnold Theiler, to whom the Committee of 

 this Association has awarded the South African medal and grant 

 (the gift of the British Association), " for achievement and promise 



