FORMATIVE INFLUENCES 587 



The trees in yards, gardens and parks are only somewhat better, 

 they are not entirely well. An atmosphere polluted by the products 

 of all our fuels except wood contains active poisons, not merely incon- 

 veniences. Because there is less soot in New York and San Francisco 

 the inhabitants speak boastingly to their less fortunate friends in Chi- 

 cago or St. Louis. But the smoke problem of cities is a problem of 

 gaseous, not solid, emanations. Smoke-consumers, so-called, add to 

 the bearableness of urban existence by reducing one disagreeable fea- 

 ture. They do not in any way affect the more serious ones. The 

 sulphurous and chlorine gases, even sometimes fluorine, escaping from 

 the chimney-tops of the office and factory buildings, and from the 

 dwelling houses, of a city of diversified activities, affect human, animal 

 and plant life. Certain wild plants which one would expect to see 

 on the tree-trunks and stone walls in towns where the air is humid, 

 are entirely absent. They have disappeared, in fact, from European 

 cities since the use of coal became general. 



If one would have a clearer view of what the effect of these gases 

 is let him go where they are discharged in greater proportions into the 

 air and note the effect on the native vegetation. Wherever smelters 

 are in operation, treating sulphurous ores of copper, zinc, mercury, 

 plants sooner or later disappear. Forest and farm suffer and finally 

 become almost or quite valueless. This is simple poisoning, resulting, 

 where the dose is great, in death. 



The egg of a gall-fly laid in or in contact with developing tissues, 

 hatching a grub which feeds and grows and excretes, becomes sur- 

 rounded by a growth imlike anything else which the leaf or branch 

 would develop, a growth of plant-tissue characteristic of the particu- 

 lar kind of plant and of the particular kind of fly. This developing 

 tumor is the result of the presence of the grub, of the formative in- 

 fluence of this parasite. Similarly, the tubercles developing on the 

 roots of many plants exhibit the formative influence of the worms or 

 of the bacteria without which they would not start, much less develop, 

 as they do. 



The life-experiences of all living things, and even the things them- 

 selves, are the joint product of substance and circumstance. Some, 

 if not all, of the substance is continuous, transmitted, from parent to 

 offspring; some, but not all, of the circumstance attending this from 

 the beginning to the end of its existence, is continuous. In the con- 

 tinuity of substance and circumstance lies the basis of the likeness of 

 succeeding generations: in the difference of circumstance from time 

 to time lies the basis of the difference which we see between offspring 

 and parents. For circumstance is but Emerson's synonym for the 

 evolutionist's word environment; and environment, on analysis, proves 

 to be the sum of the formative influences. 



