PAPERS ON BIOLOGY AND AGRICULTURE 181 



normal over periods of some few decades. Since white men 

 have been in this region only for some eighty years past, 

 no climatic change other than a very minor fluctuation 

 would be traceable, could we obtain weather records for this 

 entire period. Such a record is, of course, not to be hoped 

 for. This swing, which is a thing of the mainland en- 

 tirely and not of the islands, is seen most clearly in the 

 more advanced phases of succession, say in the white oak- 

 red oak-hickory stage, or some approximately equivalent 

 phase of the successional series, or in a later, more meso- 

 phytic, phase. Hereabouts it will become apparent that of 

 two seemingly similar assemblages one is advancing in the 

 mesophytic direction while the other is retreating in the 

 xerophytic. Thus the two assemblages of similar aspect are 

 exhibiting respectively progression and retrogression. This 

 sort of thing may be seen in portions of the Cartwright 

 woods and in areas that are near if not actually in the 

 Heckman woods near Oregon, on the west and the east 

 shores respectively. It seems rather sure that the same oc- 

 currence takes place with earlier stages of the succession, 

 but in these it is obscured and would probably require 

 statistical methods to make it clearly evident. 



Let us look into the matter of possible minor climatic 

 fluctuations. Accounts are conflicting, but from them all 

 it seems to be believed that about 1880-1900 there were 

 unusually severe winters followed by unusually hot, dry 

 summers, and that, accompanying and following this, great 

 insect damage was done to the foliage of the native vege- 

 tation, the tree growth being mentioned particularly. A 

 number of single seasons are spoken of as unusually cold or 

 dry, and so on. Unfortunately information as to plant di- 

 seases of the native vegetation in the past is and will prob- 

 ably remain unobtainable. It can only be hoped that at 

 some future time records will be made and preserved of 

 such data both for its intrinsic interest and value and for 

 its application in problems of economic importance. It is 

 now in all consideration of the vegetation an unknown 

 factor. 



Another unknown factor, but in this application one that 

 is little mentioned, is that of fires in the woodlands of the 



