1911-1912.] Elimination of A Igce in Lochs and Ponds, 429 



ities at Kew in this connection is particularly interesting. I 

 quote from the official Bulletin, as follows : " Owing to the 

 water of the lake at Kew being pumped for garden purposes 

 (including the watering of ferns and other low types of vege- 

 tation), it is considered inadvisable to use copper sulphate 

 there, but it is employed with advantage in the smaller ponds. 

 The proportion used is 1 part copper sulphate to anywhere 

 from 750,000 to 1,000,000 parts of water. . . . During the 

 last two summers a striking example of the effective use of 

 copper sulphate has been provided in St James's Park. 

 Previously, it had been a costly and troublesome matter to 

 keep the water there presentable in hot weather by employing 

 men in boats to remove the weed with rakes, &c. The copper 

 sulphate treatment was adopted, with the result, we learn, 

 that at a much less expenditure in money and labour it can 

 now be kept practically free from weed. A fact of consider- 

 able interest has also been reported by the superintendent. 

 The ponds are cleaned out triennially and the surplus fish 

 disposed of. In recent years it has been found that many of 

 the fish were badly attacked by fungus, so much so that it 

 became doubtful whether it was advisable to transfer them to 

 other waters. We learn that at the last cleansing out the fish 

 were quite free from fungoid disease, and remarkably clean 

 and silvery. This is of especial interest, because one of the 

 doubtful matters about the use of copper sulphate in water 

 was its effect on fish." ^ It will be observed that the solution 

 used on the ornamental ponds in St James's Park is much 

 stronger than that recommended by Professor West. 



At the end of July this year (1912) I again visited The 

 Haining, in order to ascertain the effect of the experiment in 

 the previous summer. I found the loch comparatively clear, 

 with no scum on its surface, and my endeavours to find any 

 trace of the Oscillatoria were unsuccessful. That it had been 

 entirely killed off it would be rash to affirm, but should it 

 again make its appearance, the copper sulphate solution, in 

 a much weaker form than before, will once more be re- 

 sorted to. 



^ Royal Botanic Garden, Kew : Bulletin of Miscellaneous Information, No. 3, 

 1912, p. 156. 



