X. 



THE INJURIOUS EFFECTS OF 

 SMOKE ON TREES. 



By John Boyd. 

 (Paper read 2nd February, igoo.) 



It requires no argument to persuade the most casual observer 

 that serious injury is done to trees in localities where there is 

 much smoke ; and not only to trees, but to all vegetation. The 

 injurious effects are most apparent on long-lived plants. On 

 annuals and herbaceous plants the pernicious results are not 

 so noticeable, although, even here, the influence of an impure 

 atmosphere is often only too evident. Even at this season, when the 

 vegetable world is, so to speak, at rest, I am sure the members of this 

 Society, who are taking frequent excursions into the country, cannot 

 fail to observe the different appearance of the grass-fields, trees 

 and plantations in this vicinity, compared with that which obtains 

 thirty or forty miles out, where there is a clear, pure atmosphere, 

 and all nature, although brown and bare, has something bright 

 and refreshing to the eye that is awanting within what may be 

 called the smoke area. This difference is even more marked after 

 a spell of close foggy weather, when everything becomes quite 

 polluted, and blackish-brown in colour. A very good illustration 

 of the blackening properties of the atmosphere around Glasgow 

 may be seen in the animal world in the case of sheep. It is quite 

 a common practice, just after harvest, for flocks of sheep or lambs 

 to be brought down from the Highlands and located in the 

 district surrounding the city, where in a few weeks these beautiful, 

 almost white, fleecy animals, become black and disreputable in 

 appearance. As a proof of the filthy state pasture assumes in the 

 winter months, it is frequently seen that if a field is left rough, 



