THE MONTHLY BULLETIN. 247 



deleterious siilpluir dioxide gas which has been poured upon it from 

 many smelters, while praetieally everything close by has succumbed. 

 hi the other tigure may be seen a manzanita bush which possessed resist- 

 ance that others growing near by did not have, and as a consequence is 

 in fine condition, while the others have perished. It is scarcely possible 

 that anything except individual differences could account for one tree 

 or plant being killed, while another standing alongside escaped. Of 

 course, in cases where a great many trees escaped injury, while those 

 about them had not, such could be accounted for by natural protection 

 of the former through being situated favorably with reference to the air 

 currents carrying the gas. A parallel case of individual resistance and 

 natural protection of certain often quite small areas, is frequently seen 

 in sections of frost injurj^ to trees and fruit. One tree standing in an 

 orchard may have a big crop of fruit, wliile many other trees of the 



Fig. 52. — Miles of bare hills due to smelter fumes damage. (Original.) 



same variety surrounding it will have none. Again, an orchard on one 

 side of a roadway may have the entire crop of fruit destroyed by frost 

 and on the other side a similar orchard may have a full crop at picking 

 time. This being true in the case of frost injury it is not at all strange 

 to find that the same thing holds true in sections of sulphur dioxide 

 injury, and can be accounted for (first) from the fact that different 

 individuals, among trees as well as among people, possess different 

 degrees of resistance to unfavorable conditions, and (second) because of 

 the erratic nature of air currents which possibly we shall know more 

 about when more people have acquired the flying habit. This being 

 true, is it any wonder that one man 's field of grain or alfalfa will suffer, 

 while a neighbor's will experience no injury whatever, or that one part 

 of a field will show burning and another part none? Yet one of the 

 commonest stumbling blocks placed in the way of those who are called 

 upon to prove that injury has been done, is that of good crops adjacent 



