PLANKTONIC STUDIES. 573 
II.—PLANKTONIC STUDIES. 
My own investigations on the organisms of the plankton were begun 
thirty-six years ago, when I got my first conception of the wonderful 
richness of the marine fauna and flora in the North Sea. Accepting 
the kind invitation of my ever-remembered teacher, Johannes Miiller, 
J accompanied him in the autumn of 1854 on a vacation trip to Helgo- 
land, and was introduced by him personally into the methods of plank- 
ton fishery and the investigation of the pelagic fauna. There, during 
August and September, I accompanied him daily on his boating trips, 
and under all conditions of the rich planktonic captures I received from 
him the most competent instruction, and pressed with corresponding 
eagerness into the mysteries of this wonderful world. Never will I for- 
get the astonishment with which I first beheld the swarms of pelagic 
animals which Miiller emptied by inversion of his “fine net” into a glass 
jar of sea water—a confused mass of elegant meduse and glistening 
etenophores, swift-darting sagittas and snake-like tomopteris, copepods 
and schizopods, the pelagic larve of worms and echinoderms. The 
important stimulus and instruction of the founder of planktonic inves- 
tigation has exercised a constant influence on my entire later life, and 
has given me a lasting interest in this branch of biology.* 
Two years later (in August and September, 1856), while at Wiirtz- 
burg, I accepted the invitation of my honored teacher, A. Kélliker, to 
accompany him to Nizza, and, under his excellent guidance, became 
acquainted with the zoélogical treasures of the Mediterranean. In 
company with Heinrich Miiller and K. Kupffer, we investigated espe- 
cially the rich pelagic animal life of the beautiful bay of Villafranea. 
There, for the first time, I met those wonderful forms of the pelagic 
fauna which belong to the classes of the siphonophores, pteropods, and 
heteropods. I also there first saw living polycyttaria, acanthometra, 
and polyeystina, those phantasmic forms of radiolaria, in the study of 
which I spent so many later years. 
Johannes Miiller, who was at this time at Nizza, and had already 
begun his special investigation of this latter order, called my attention 
to the many and important questions which the natural history of 
these enigmatical microscopical organisms present. These valuable 
suggestions resulted some years later in my going to Italy and spend- 
ing an entire year in pelagic fishing on the Mediterranean coast. Dur- 
* When at Helgoland, investigating the wonders of the plankton with the micro- 
scope, Johannes Miiller, pleased with the care and patience with which his zealous 
students tried to study the charming forms of medus# and ctenophores, spoke to me 
the ever-memorable words, ‘There you can do much; and as soon as you have 
entered into this pelagic wonderland you will see that you can not leave it.” 
