liv PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



Prof. Perctyal said the matter was obviously one of fact, and what 

 was wanted was more evidence. He doubted whether any of those 

 present had lived long enough to settle such a question, especially in 

 the case of long-lived plants such as vines. The idea of deterioration 

 was no doubt widely spread. When they heard, as in the case of the 

 potato, that certain varieties had been in cultivation for a long time, it 

 did not touch the point. A large number of varieties might have died out 

 very much more quickly than others which may have had more vitality. 

 Certain it was that some varieties had disappeared, but why was not 

 quite clear. There was evidence that they got weaker and weaker, and 

 that was why they had been discarded for their poorness. A hundred 

 years ago — in fact, in the middle of the eighteenth century — there was 

 evidence of very great difficulty in rearing potatoes, which in many cases 

 refused to come above ground. Some such effect was noticed nowadays 

 by growers, and it was no doubt due to a weakening cause. If that were 

 the case, he personally thought it strongly favoured the disappearance 

 of the varieties vegetatively reproduced. To ask why was like asking 

 why old age occurred. We did not know what old age was. Human 

 beings did not live for ever — nor did trees. There seemed to be a 

 distinct life-period for all these things, after which they died down from 

 want of vitality. Everything underwent repair, and he believed the 

 repair was not perfect, and that the life-machinery gradually weakened 

 and vitality was lost. The question would only be settled, if at all, by 

 experiments. 



Mr. Odell stated that, after many years of experiments, he had found 

 that 1 Magnum Bonum ' grown for four years running on a heavy clay 

 loam in Middlesex was completely worn out, and in two years the 

 produce was reduced by 50 per cent. 



Dr. Masters : How would it have been on another field ? 



Mr. Odell said he could not answer the question. In the case he 

 mentioned it was the same soil, but not the same plot. 



Mr. Druery : Would that not imply that the soil was not suitable for 

 potatoes ? — and that would be begging the whole question. 



Mr. Worsley said he got some advertised disease-proof potatoes, but at 

 the end of eight years all the potatoes were diseased. 



Mr. Douglas recalled how in his young days they had two deliciously 

 flavoured potatoes, ' Buffs ' and ' Dons,' but in 1845 they were practically 

 exterminated. The people then took to the white potato, but they were 

 nothing like the others in quality. It was about that time that guano 

 was introduced, and many farmers thought that was the cause of the 

 disease. He did not know whether there was any truth in that, but he 

 had come to the conclusion that artificial manures favoured the produc- 

 tion of disease. In Essex they had potatoes for many years, but the 

 tubers deteriorated. They used to grow 100 acres of potatoes, and it 

 paid to send to Scotland for the seed. Owing to weakness many of the 

 potatoes never ripened, and degeneration soon followed. He could not 

 say what was the cause of the degeneration, unless it was artificial 

 manures. 



Mr. Foster was of opinion that there was no doubt that potatoes did 

 deteriorate after they had been grown in the same soil for a number of 



