6.—PLANKTONIC STUDIES: A COMPARATIVE INVESTIGATION 
OF THE IMPORTANCE AND CONSTITUTION OF THE PELAGIC 
FAUNA AND FLORA. 
By ERNST H2CKEL. 
[Translated by George Wilton Field.] 
TRANSLATOR’S PREFACE. 
Prof. Heckel’s ‘“Plankton-Studien” first appeared in the Jenaische 
_ Zeitschrift, vol. XxXv, first and second parts, 1890. It was immediately 
published in separate form by Gustay Fischer, of Jena, and attracted 
much attention on the Continent and in England. The subject, “a 
comparative study of the importance and constitution of the marine 
fauna and flora,” is presented in Prof. Heckel’s usual pleasing style, 
and the work can not fail to be of value to all interested in the bio- 
logical sciences, to the general reader as well as to the specialist. It 
derives especial interest in connection with the work of the Fish Com- 
mission, from its broad discussion of those many important elements 
which enter into the food supply of all pelagic fishes, such as the 
mackerel and menhaden, and, considering the extensive physical inves- 
tigations now being conducted in our coast waters by the schooner 
Grampus, its publication at the present time will prove exceedingly 
advantageous. 
The terminology used by Prof. Heckel may at first seem formidable, 
but this difficulty is more fancied than real. The terms are formed 
upon correct analogies, and most of them will probably find a perma- — 
nent place. The definite restriction of the meaning of terms is a funda- 
mental necessity in every science, and for the lack of this the branch 
of biology here considered is in a very unsatisfactory condition. The 
author, first of all, proposes certain terms with a definite meaning. — 
The word “plankton,” from the Greek ziayzrés, wandering, roaming, was, 
I believe, first employed by Hensen in place of the German “ Auftrieb,” 
to designate all plants and animals found at the surface of the ocean 
which are carried about involuntarily in the water. Heckel adopts this 
term, but objects somewhat to the meaning at present attached to it. 
Particularly valuable for us is the general review which the author 
gives of the discovery and growth of our knowledge of this branch, 
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