10 THE SMOKE INVESTIGATION 



Observations and Experiments 



Aside from the general observations and experiments 

 which were carried on, circular letters were sent out to 

 various florists and gardeners in and near Pittsburgh. 

 Following is a sample of the inquiries in the circular let- 

 ters and of the replies received : 



1. Date of reply : A. About July, 1912. 



2. State your general business (such as Florist, Gard- 

 ener, etc.) : 



A. About thirty replies were received, these being 

 almost equally distributed between florists and gardeners. 



3. What plants native to Pittsburgh and vicinity do you 

 consider grow poorly or not at all, because of the smoke, 

 soot and gases? 



A. Evergreens, Sugar Maples, and other plants in 

 more or less impoverished condition. 



4. What plants introduced into Pittsburgh and vicinity 

 thrive poorly or not at all, because of the injurious effects 

 of smoke and gases? 



A. Evergreen trees, Spiraea and White Oak. 



5. What plants native to Pittsburgh and vicinity thrive 

 well in spite of the smoke and gases? 



A. Rhus, Salix, and grasses. 



6. What plants introduced into Pittsburgh and vicinity 

 do well in spite of the smoke and gases? 



A. Ailanthus, Norway Maples, Platanus occidentalis, 

 and Syringa. 



7. WTiat is the character of the injury done to your plants, 

 or any plant which you have dbserved? 



A. Stomata stopped, buds and foliage have the ap- 

 pearance of being subjected to intense heat or fire, and 

 dying of trees from the top down. 



8. How much of this injury do you attribute to smoke, 

 and how much to gas and other causes? 



