395 



ize environmental fluctuations and to obviate their catastrophic 

 results, which may be seen in their maximum violence in 

 channel waters, and in a lesser degree in the lakes thus far ex- 

 amined. 



COLLECTIONS. 



This station was opened June 7, 1 894, and collections were 

 continued until the close of operations on March 28, 1899. In 

 all, 99 collections were taken, distributed in the several years 

 as follows: 5, 14, 27, 18, 25, and 7, with but few exceptions at 

 approximately a monthly or fortnightly interval. It was only 

 in the spring and summer of 1896, when an interval of 7-10 

 days was adopted, that the interval is brief enough to enable 

 us to trace the movement in production with any degree of 

 fullness. At other seasons the data are suggestive, but not 

 conclusive, of its course. The relatively smaller number of 

 collections made at this important station is due to its distance 

 from our center of operations, the round trip from Havana to 

 the lower station in low-water conditions exceeding 25 miles. 

 The difficulties of access were greatly increased when at low 

 water it was necessary to make the trip from the outlet of the 

 slough by rowboat, and to drag or push this over the soft mud 

 and through the dense vegetation at the upper end of the lake, 

 and when, in winter, at low water, the boat and outfit had to 

 be dragged across the frozen bottom-lands. 



The locations at which collections have been made are 

 principally the two marked on the map (PL II.). The lower 

 one was used exclusively in 1894 and 1895, and thereafter 

 when access to the lake was had through the cut road. The 

 location off Sand Point, at the upper end, was used when the 

 lake was entered by way of the slough. Both were in the open 

 central region, well out in the vegetation-free area, though in 

 1895 and 1896 the lower station was encroached upon some- 

 what by shifting masses of Ceratophyllum. In a few instances, 

 owing to high southwest winds and the dragging of the waves 

 in the shallow lake, it was not possible to maintain an anchor- 



