THE RELATION OF PLANTS TO TIDE-LEVELS. 
A STUDY OF FACTORS AFFECTING THE DISTRIBUTION OF MARINE PLANTS 
AT COLD SPRING HARBOR, LONG ISLAND, NEW YORK. 
By Duncan S. JOHNSON AND HARLAN H. YorK.! 
I. INITIATION OF THE WORK; ITS PURPOSE; 
ACKNOWLEDGMENTS. 
The present studies were begun, in the summer of 1905, by Duncan S. Johnson 
and Mary Lentz Johnson, at the Biological Laboratory of the Brooklyn Institute 
of Arts and Sciences, at Cold Spring Harbor, New York. They have been 
continued during the summers of 1906 to 1913 by the authors. 
During the progress of the work, which sometimes demanded the cooperation 
of several men working at once, other members of the Laboratory have aided us, 
among them Messrs. W. H. Brown, G. C. Fisher, W. E. Maneval, and L. H. 
Sharp. Thanks are due especially to Dr. C. B. Davenport, Director of the 
Laboratory, who afforded facilities for carrying on the work and gave suggestions 
concerning the construction of the maps. Professor Francis E. Daniels, of St. 
Johns College, Maryland, rendered valuable aid in making tide records and in 
surveying parts of the harbor. We have also to thank Professor H.S. Conard, of 
Grinnell College, Iowa, for contributing an important section of the descriptive 
portion of this paper. In the summer of 1909 Professor Conard, with the aid 
of Mr. Paul M. Collins, plotted in minute detail the distribution of the vascular 
plants of a carefully selected area on the Spit and one on the Marsh. The 
- results are given in plates XIv, XxI, and xx11, and in the explanations of these 
on pages 113 to 121. In the summer of 1910 Miss Stella G. Streeter, of Jersey 
City, made a study of the rate of growth of certain Ulvacese, Fucacee, and 
Rhodophycee, of the salinity of the water in several tributaries of the harbor, 
and of the soil-water at several points on the Marsh. Her results are embodied 
in Sections III and IV. Dr. A. F. Blakeslee secured specimens of alge for us 
in the winter of 1912-13. To Mr. F. 8. Collins, of Malden, Massachusetts, 
and Dr. Albert Mann, of Washington, D. C., we are under obligation for the 
identification of various alge and diatoms. 
These studies have been confined chiefly to the small “ Inner Harbor,” on 
which the Biological Laboratory is located. The field work has been done by 
both authors in the time they could spare from their work of instruction in this 
Laboratory, during July and August of the years mentioned. Visits have also 
been made to the harbor in April, in June, in late September, and at the end of 
November, for the sake of comparing the condition of the vegetation at these 
times with that found in midsummer. This paper has been written by the 
senior author, except the chapters attributed to others, below their titles. 
1 Botanical contribution from The Johns Hopkins University No. 42. 
