i. 
we 
262 
REPORT on TWO COLLECTIONS of TROPICAL 
and MORE NORTHERLY PLANKTON. 
By Isaac C. THompson, F.L.S. 
With Plate XV. 
[Read December 11th, 1899. ] 
THE two collections of plankton here treated of were 
kindly handed to me for examination by my friend Prof. 
Herdman, F'.R.8., the first having been collected by his 
cousin, Capt. FH. H. Wyse, of the ship ‘‘ Johannesburg,” and 
the second by his brother, Mr. G. W. Herdman, B.Sc. 
As a considerable portion of the area traversed was, in the 
two cases, almost identical, it was thought best to include 
them within one Report. 
Both travellers were provided by Prof. Herdman with 
the needful supply of tow-nets, bottles, and preservative 
fluids, the general plan followed being that successfully 
carried out by Prof. Herdman himself while crossing the 
Atlantic in the summer of 1897. 
The modus operandi adopted for continuous collecting 
by means of tow-nets fixed to running water taps while a 
vessel is steaming at full speed, was fully described and 
figured by Prof. Herdman in L.B.S.Trans., vol. XIL., 
p- 33. As the paper referred to is out of print, and is 
frequently enquired for, I have thought it well to quote here 
in full the portion referred to :— 
“The method adopted was the ‘pump’ one, by which 
the nets are not immersed in the sea, but are merely 
used to strain the organisms from the sea-water which has 
been pumped into the ship. My nets were made of the 
