230 
BIOLOGY: A. P. DACHNOWSKI 
Proc. N. a. S. 
in the accompanying interstadial time, with a tendency toward optimum 
conditions which favored the growth of forests. It is quite probable that 
the last climatic wave or belt, possibly in diminishing intensity, continues 
to shift northward at the present time. 
5. In the past sixty centuries the power of nations has been moving rather 
steadily northward, and the higher production of agricultural crops has 
occurred in general near the northern limits of distribution. It is signifi- 
cant that this northward tendency in agricultural and social development 
seems to be continuing and that it appears to be correlated with practically 
the same course of events which is shown in Tables I to IV. 
Profile Sections of Peat Deposits 
I, II, VI and VII from Botanical Gazette,^ 72, 57-89, 1921. (4) 
III. Profile of Kankakee Marsh near Crumstown, Indiana. 
IV. Cross Section of Dismal Swamp, Virginia, generalized from soundings and ex- 
posures along the feeder ditch and the Dismal Swamp canal. 
V. Cross section of Torry Island in Lake Okeechobee, Florida, also near Okeelanta, 
about five miles south from the lake shore. 
VIII. Sounding on peat experiment sub-station near Sanilac, Michigan. 
IX. Profile along barge canal near James street bridge at Rome, N. Y. 
X. Sounding in central location of peat deposits at Chassel-Klingville, Michigan. 
XI. After Weber. (16) XII. After Rankin. (11) 
XIII. After Shreiber. (14) XIV. After Sernander. (13) 
XV. After Erdtman. (6) XVI, XVII. After Docturowski. (5) 
1 Brooks, C. E. P. Evolution of climate in North-west Europe. Quar. J. Roy. Meteorol. 
.Soc, 47, 1921 (173-194). 
2 Chamberlin, T. C. & Salisbury, R. D. The pleistocene or glacial period. Geology, 
Vol. 3, 1906. 
3 Coleman, A. P. Length and character of the earliest interglacial period. Bull. 
Geol. Soc. America, 26, 1915 (243-245). 
4 Dachnowski, A. P. Peat deposits and their evidence of climatic changes. Chicago, 
JBot. Gaz., 72, 1921 (57-89). 
^ Docturowski, V. S. Vidy torfa. (Les especes de tourbe) Viestnik torfianovo diela, 2, 
1915 (273-304). 
^ Erdtman, 0. G. E. Pollenanalytische Untersuchungen von Torfmooren und Mari- 
nen Sedimenten in Siidwest-Schweden. Arkiv. Bot., 17, 1921, No. 10, (73-79). 
• Geer, G. de A geochronology of the last 12000 years, ii Internal. Geol. Kong. 
Stockholm, 1910, 1912 (241-253). 
^ Lever ett, F. and Taylor, F. B. The pleistocene of Indiana and Michigan and the his- 
tory of the Great Lakes. U. S. Geol. Survey, Monographs, 53, 1915 (529). 
9 Osborn, H. F. Men of the Old Stone Age, 1916. 
" Penck A. and BrUckner, E. Die Alpen im Eiszeitalter, Leipzig. 3 vols. 1901-1909. 
11 Rankin, W. M. The lowland moors (mosses) of Lansdale (North Lancashire) and 
their development from Eens. Types of British Vegetation, 1911 (256-259). 
12 Reeds, C. A . Graphic projection of Pleistocene climatic oscillations. Bull. Geol. 
Soc. of Amer., 26, 1915 (106-109). 
1^ Sernander, R. On the evidences of Postglacial changes of climate furnished by 
the peat-mosses of Northern Europe. Geolog. Fcreningens fdrhandl., Stockholm, 30, 
