269 
February, March, and April have been covered by collections 
at intervals of five days or less, and from July 14, 1897, to March 
28, 1899, a period of nearly twenty-one months, the series of 
regular weekly collections is almost unbroken. The following 
table gives the distribution of the collections by months in the 
several years. 
DISTRIBUTION OF COLLECTIONS BY MONTHS. 
Year | Seon lee le selesal ale Leah acl | ore |s 
Slee (eta lere to lo bela te 
1894 2 2 2 I I | I 10 
1895 I 2 Ved We el 151 Sh 4s 8 [50 
1896 9| 4 5 5| 9 Fl SP Ca Va ay 3 2 Ta 2 eG 
1897 2d tah | RE] Vt He Oral fan |e i 2 Ps | 
ISOC RS eSH se Stee es Se aul eS Wray bas Wei Galik het 62 
1899 | 5] 4] 4 | 13 
otal | 2774/15) ES.) 12) 05) | 160) 30 35.) 2701 17 | 16 20 |235 
The distribution by months is such that a fair basis is 
formed for the determination of the seasonal fluctuations, 
since every month is represented by a considerable number of 
collections. The larger numbers in the summer months re- 
sult from the fact that the field station was always open dur- 
ing this season. The total number, 235, is more than twice 
that made at any other station in our field of operations, and 
affords the most complete and longest series in our collections. 
It is fitting that in this our most variable station the interval 
between collections should be least. The total period covered 
by our collections here is a little over fifty-seven months, and 
the average interval between collections 7.4 days. I know of 
no series of quantitative plankton collections, in any waters, of 
equal range or time, variety of season, and brevity of interval. 
THE LOCAL DISTRIBUTION OF THE PLANKTON AND ITS RELATION TO THE LIMIT 
OF ERROR IN THE METHOD, 
The investigator of plankton problems is constantly con- 
fronted by the question of the extent of the error resulting 
