Introduction 



i 

 The present paper attempts to determine, primarily, 



the effect of the soot in smoke and included materials upon 

 plants. General observations have been made by the writer 

 in the following localities: certain of the pu'blic parks in 

 Chicago; in Pittsburgh and vicinity; along the railroad 

 between Pittsburgh and Tyrone ; and at State College and 

 vicinity. Specific observations by means of controlled 

 laboratory experiments were made at State College, Penn- 

 sylvania. While the observations have not been so numer- 

 ous as might be desirable, yet the writer feels that they 

 will warrant the conclusions drawn. He has the feeling 

 that the data obtained have been somewhat meager owing 

 to the fact that the investigation has not been prolonged 

 over a sufficiently long period of time. 



