157 
cycle of seasonal fluctuations more or less approximates year 
after year, and not a few of the important environing factors 
are operative in much the same way upon by far the larger 
part of the biological area. There is thus a common basis 
upon which the other less constant factors produce their effect. 
The best justification, however, for the use of the term lies in 
the results of our work, which show a biological assemblage 
adapted to this complex environment, and exhibiting in some 
of its phases at least as much uniformity as the more stable 
factors of its surroundings. 
During 1894 and the early part of 1895 readings were re- 
corded only at occasional intervals owing to the fact that the 
Station was occupied but part of the time, its work being as yet 
in the preliminary stage. From August: to October, 1895, bi- 
daily readings were made by Mr. Newberry at a gage located 
by us at our field headquarters and based upon the government 
gage on the protection at the wagon-bridge at Havana. From 
October, 1895, to January, 1896, the readings were taken by 
Mr. Hempel at the government gage, and since that time bi- 
daily or daily readings have been taken under the direction of 
the city authorities of Havana. These readings are given in 
the tables which follow. 
