1914 ] 
Jackson: Land Vertebrates of Ridgeway Bog 
47 
seem to have entered the region directly from a southeastern 
center of dispersal; among these are Amelanchier canadensis j Acer 
saccharum, Rana cantabrigensis, Storeria occipitomaculata, Buteo 
platypterus, Vireosylva olivacea, Dendroica vigorsii, and Seiurus 
aurocapillus. Acer saccharum may have had a southern center of 
dispersal rather than an eastern one. Odocoileus and Mephitis 
without doubt ingressed from the south. It should be noted that 
the biota of the Hillside Association as a whole tends to show 
more southerly and southeasterly affinities than that of the Cedar- 
Balsam-Hemlock Association ; and this is more particularly notice- 
able in the fauna. I am unable to account for the scarcity of the 
crow in this bog, nor can I understand why I have observed it 
only in the Hillside Association; elsewhere in the region it occurs 
frequently among tamaracks and spruces. 
It has been written that “if the organization of ecological 
materials is to be brought about in correlation with natural laws, 
then agricultural communities are essentially useless subjects for 
study’’ (Shelf ord, 1912b, p. 349). Admitted the general appli- 
cability of the truth of this statement, there are nevertheless 
cases where the clearing of timber, the draining of swamps, and 
the various other accompaniments of agricultural development 
may be of exception^ advantage and value in ecological and bio- 
geographical investigations, provided always that preceding this 
development detailed studies have been made in the region; 
agricultural development may then offer opportunities for experi- 
mental field studies by the changes brought about through the 
development, the control being furnished by the conditions origi- 
nally existing. The general region of Ridgeway Bog, for several 
miles in all directions, up to about the year 1882 remained cov- 
ered with virgin coniferous forest, but about that date the lum- 
bering industry opened at Rhinelander and within the next fifteen 
3 ^ears all the heavier timber was cut except in isolated groves. 
We can only hazard a guess at what transformations might take 
place in the biota of this region had this forest been untouched by 
man, but there is considerable possibility that, at least in places, 
there might be an ingression from the south of a biota of a decidu- 
ous forest type. I base this assumption upon the fact that a few 
plants of the deciduous forest type had already ingressed this region 
in the time of its maximum coniferous forestation; among these 
