28 PROCEEDINGS OF THE ALBANY MEETING 



and, moreover, King and Jeffreys found the peaty soils in Wisconsin were 

 usually alkaline from excess of MgCOs, so much so that crops were decidedly 

 injured by the salt. I have a little new light myself which may develop into 

 something fairly important as one factor, but T am going to investigate it 

 somewhat before I spring it, but it is promising, more so than anything T have 

 struck lately ; but I am quite sure that no one factor is the only one, so I am 

 simply looking for the controlling one. It is easier for most of us to speculate 

 in the study than to investigate in the field and laboratory, and often after we 

 get results it is difficult to know what to do with them !" 



"Ann Arbor, Michigan, Dccemhcr 8, 1904. 



"About the prairie business, I will give you the benefit of my cogitations 

 (not my experiments) on the subject immediately. From my observations in 

 the marsh and prairie lands in Tuscola County and in other parts of the State, 

 I have attributed the absence of trees in these places to three causes: (1) 

 The high water for seAcral weeks in the spring, which prevented germination 

 taking place or submerged the seedlings for a fatally long period after germi- 

 nation. (2) The absence of mineral soil in sufficient quantity to permit the 

 growth of trees during the early part of their life history. (3) The generally 

 high soil water level of these places. A fourth and perhaps generally impor- 

 tant factor might be taken into account — that is, the dense growth of sedge.^ 

 and grasses in the prairie soil — which first keeps the seeds of trees from reach- 

 ing the ground and then, later, overshadows those that do reach it and pre- 

 vents germination or destroys the young plants by shading them too much. 



"To support these hypotheses there is the following : When I first went over 

 the prairies in Tuscola County, there were no trees or shrubs except on the 

 'islands' of sand in the marshes, and the treeline was very definite and sharp 

 inshore, with no fringe of young growth reaching out on to the prairie ; but 

 the last time I was over there not only shrubs, but trees, especially poplars 

 and willows, were forming dense thickets all over the area, and for several 

 hundred feet out from the 'treeline' were young trees of the species common 

 in the woods, which were four or five years old, making a thrifty and well 

 marked fringe to the old woods. I attributed this sudden development in this 

 type of vegetation to the building of roads across the prairies and the conse- 

 quent and subsequent ditching which has covered the whole area with a net- 

 work of drains, which not only carry off the water rapidly in the spring, but 

 lower the water level in the soil throughout the rest of the year, and this tends 

 to diminish the humus content by drying, kills out the grasses and sedges, and 

 in various ways makes the soil conditions favorable to tree growth, and as the 

 trees are always standing around the edge waiting to get in, there is no trouble 

 about their advancing as soon as they can without getting their feet too wet. 

 On the sand islands the soil was slightly above the general level and sufficiently 

 porous to drain itself readily and quickly after the spring floods subsided. I 

 have never given the Saint Clair flats attention enough to know whether the 

 same state of affairs is to be found there as around Saginaw Bay or not, but 

 expect conditions are about the same." 



