576 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
which I owe to these are already embraced in my monographs on these 
three classes in the Challenger Report, and in the pretace I have ex- 
pressed to Capt. Rabbe my sincere thanks for his very valuable aid. 
Of all expeditions which have been sent out for investigating the 
biology of the ocean, that of the Challenger was, without doubt, the 
greatest and the most fruitful, and I recognize it with additional grati- 
tude since I was permitted for twelve years to take part in working up 
its wonderful material. When, after the returi of the expedition, I was 
honored by its leader, Sir Wyville Thompson, by being summoned to 
work up the extensive collection of radiolaria, I believed, after a hasty 
survey of the treasures, that I could complete their investigation in the 
course of three to five years; but the further I proceeded in the inves- 
tigation the greater seemed the assemblage of new forms (4, p. XV), and 
it was a whole decade before the report on the radiolaria (part XVIII) 
was completed, Three other reports were also then finished—on deep- 
sea horny sponges (part LXXXII), on the deep-sea meduse (part XII), 
and on the siphonophores (part XxviI) collected by the Challenger. 
The comparative study of these extremely rich planktonic treasures 
was highly interesting and instructive, not only on account of the daily 
additions to the number of new forms of organisms in these classes, 
but also because my general ideas on the formation, composition, and 
importance of the plankton were enriched and extended. I am sin- 
cerely thankful for the liberality with which Sir Wyville Thompson, 
and after his untimely death (1882) his successor, Dr. John Murray, 
placed these at my entire disposal. 
A record of the 168 stations of observations of the Challenger ex- 
pedition, whose soundings, plankton results, and surface preparations 
I have been able to investigate, has been given in § 240 of the report 
on the radiolaria (4, p. CLx). The number of the bottles containing 
plankton (from all parts of the ocean) in alcohol amounts to more than 
a hundred, and in addition there are a great number of wonderful 
preparations which Dr. John Murray finished at the different obser- 
vation stations, stained with carmine and mounted in Canada balsam. 
A single such preparation (for example, from station 271) contains 
often 20 to 30 and sometimes over 50 new species. Since the material 
for these preparations was taken with the tow net, not only from the 
surface of all parts of the sea traveled by the Challenger, but also from 
zones of different depths, they make important disclosures in morphol- 
ogy aS well as in physiology and chorology. To the study of these 
station preparations I am indebted for many new discoveries. I have 
been able to examine over a thousand (4, p. 16). 
if I here refer to the development and extension of my own plankton 
studies, it is because I feel compelled to make the following brief sum- 
mary of results. I am not now in a position to give the proofs in detail, 
and must defer the thorough establishment of the most weighty 
