796 MODIFICATIONS OF ASPECTS OF ORGANIC NATURE 



will I content myself with simply repeating Mr. Marsh's summing 

 up of the matter in the short way in which long words so often 

 (literary critics notwithstanding) enable us to sum up the results of 

 a long investigation, and saying with him that (p. 300 1. c.) the 

 forest's 'general effect is to equilibrate caloric influences and 

 moderate extremes of temperature.' But I will firstly, upon 

 this occasion, repeat what I have often heard my late and much- 

 lamented friend, Mr. Wm. Menzies, the author of the splendidly- 

 illustrated book, ' Forest Trees and Woodland Scenery as described 

 in Ancient and Modern Poets,' say, to the effect that England is 

 after all as well-wooded a country as probably any other civilised 

 one in the world, adding that Sir John Lubbock has, as I think, 

 either in some volume which he has contributed to science, or in 

 some return which he has extracted from Parliament, established 

 the same fact. And, remarking that if we couple with this fact the 

 consideration that this favourable numerical representation of trees 

 is not due to the existence of large forests, we find therein an illus- 

 tration of the working of certain peculiarities of our social and 

 political condition as compared with those of other countries, which 

 I leave to your consideration ; I pass on, secondly, to say a few 

 words as to the influence which trees exercise in the way of modify- 

 ing climate locally by means of their leaves. Clearly this comes 

 fairly under the title of my lecture. Man can cut down ' the goodly 

 fir-trees ' and other trees too, ' Laubholzer ' as well as ' Nadelholzer,' 

 of an entire country ; he can burn them, and by his domesticated 

 goats and cows and camels he can prevent their suckers and their 

 seeds from replacing them by fresh plants. What consequences 

 follow when the square area which a tree in full leaf represents is 

 abolished ? Firstly, whatever else may be disputed, there can be 

 no doubt the loss of this square area means the loss of a very con- 

 siderable area upon which dust and particulate matter can be caught 

 and filtered out of the atmosphere. The more sticky the leaves, of 

 course the more perfect the interception. And as modern investi- 

 gations, such as those which Mr. John Simon, C.B., used to have 

 carried on whilst in the Medical Department of the Privy Council 

 OflBce, have taught all those who have ears to hear, even if not also 

 eyes to see, that the germs of many or most infectious diseases are 

 particulate^^ we can understand how it is that from so many 

 * We have such accounts from Ravenna and Beyrout; from the East and the 



