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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



ever ready to give help and information on matters touch- 

 ing the chemistry of fog, which he has made his own. 

 It has always been my regret that from the special nature 

 of my work I have been unable to render any adequate 

 return to him in kind. To Mr. H. J. Veitch we are under 

 singular obligations. He has not only placed his rich collec- 

 tions of stove and greenhouse plants at my sendee for observa- 

 tional purposes, but has also been good enough to construct a 

 small experimental laboratory at his nurseries in the King's 

 Road, Chelsea, to forward the purposes of the investigation. 

 Finally, I must thank the Director of the Royal Gardens, Kew, 

 and the Assistant-Curator, Mr. Watson, as well as many 

 friends, including my colleagues on the Scientific Committee, 

 for help in various ways. — F. W. 0.] 



In my first report * the general scope of the investigation, 

 which the Committee desired me to undertake, was explained, 

 and some of the early results of the inquiry described. Of the 

 actual effects of our London fogs upon vegetation I have had 

 ample opportunity for study. During the winter of 1890-91, as 

 has been alluded to in my former report, two spells of fog were 

 experienced of almost unprecedented severity ; last winter the 

 Christmas fogs alone call for special mention ; whilst this winter, 

 up to the date of presenting this report, though foggy weather 

 has been certainly prevalent, the damage to plants has been 

 relatively slight, or at any rate only locally severe. I have thus 

 been able to compile an exhaustive list of those cultivated plants 

 which suffer from this cause, with notes on the nature of the 

 injuries incurred. 



The extension of the work of recording the effects of separate 

 fogs upon the same collections of plants, during several winters, 

 has ensured the possibility of comparing the effects of fogs which 

 differ from one another in essential respects. Physiological 

 experiments on so gigantic a scale could not have been obtained 

 by any other means, and the comparative results have made it 

 possible for mo to speak with conviction on at any rate one 

 important question. This will be entered upon in due time. 



A constant source of difficulty arises from the fact that we 

 are so ignorant of the exact nature of the substances which are 



* Journ. Boy. Hort. Soc. vol. xiii. p. 139. 



