CIVILIZATION AND VEGETATION 331 



sheds and to conserve and control the yearly run-off, are annually placed 

 in jeopardy by the railroads. Last year, disastrous fires in the far north- 

 west, and the less extensive fires of Wisconsin and Minnesota in the 

 summer preceding, only too plainly showed this. So dreadful has been 

 the loss of human life and of property from this cause that the substi- 

 tution of sparkless fuel-oil on locomotives traversing forested areas is 

 now not only urged by the forest service, but being seriously considered 

 by the railway companies. Until electric traction or sparkless fuel is 

 employed, each dry season will bring its record of destruction along 

 the tracks of civilization through forest and grazing land. 



Peaching almost as far from its source as the fires accidentally set 

 by civilization, is the destruction of vegetation by certain forms of 

 industry. The damage is done in two ways, by drainage and by fumes. 

 The composition of ordinary domestic drainage is disturbing enough to 

 vegetation. I have had occasion to notice this along the shore of 

 Monterey Bay. When I first saw these waters they were bordered on 

 one side by the towns of Monterey and Pacific Grove, sleeping peace- 

 fully, the one after a somewhat turbulent past, the other on federal and 

 denominational pensions. Between tide marks and further out were a 

 fauna and flora so rich and so varied that a few years earlier, when the 

 whole coast of California was open for such a choice, this had been 

 selected as the best location for the Marine Biological Laboratory of 

 Stanford University. So far as I can see, the fauna and flora are as 

 rich to-day as then, but with the recent rapid increase in population of 

 these two towns and the consequent increase in sewage pouring into 

 the bay at no great distance below low-tide mark, there has been a 

 decided increase in the quantity of diatoms living attached to the sea- 

 weeds growing between tide marks. The body of water in Monterey 

 Bay is so very large and so thoroughly mixed by the tides, and the 

 volume of sewage discharged into it from the towns on its shores is still 

 so small in comparison, that the sea-water, even now, deserves to be 

 called pure. But it is no longer perfect purity. Its increasing though 

 still relatively slight pollution is shown by the change in the balance of 

 the population between tide marks, by indicators exceeding in sensi- 

 tiveness those of the chemical laboratory, by living things. We all 

 know that, when pollution goes further, certain plants are no longer 

 found in stream and bay; river and mud-flat become huge cultures in 

 which coarse algas and offensive bacteria flourish. 



In all such changes as these, however, there is only a change, not a 

 decrease in the value of the water as a nutrient solution. Nothing 

 poisonous has been added to it, only substances which so abundantly 

 nourish bacteria, blue-green algse, diatoms and coarse green alga?, that 

 other forms become more or less crowded out. This is so common an 

 effect of civilization on vegetation that we think nothing of it. On the 



