NOTES AND MEMORANDA. 393 
water without disturbing it so much as to interfere with its 
ordinary conditions. Raking it with a towing net was in 
one sense a clumsy operation, for all the minute forms which 
had not been eaten by larger ones escaped, and the captives 
were drawn through the water ina way likely to influence 
both their appearance and their action. Ina ship at sea and 
under steam it is possible to raise water for examination with 
very little disturbance, if you can “ fish” from some part of 
the ship where the forward swing of your apparatus as you 
raise it from the water does not bring it into contact with 
any part of the vessel. 
The dipper should be a hemispherical tin cup leaded on 
one half the edge in such a way that it will scoop under the 
water that it raises, which can then be gently poured into a 
beaker for examination. Lowering down the beaker itself is 
a better plan still, for the second disturbance is thus avoided. 
In this way I have frequently captured Appendicularia 
without frightening it out of its “ haus,” and I have never 
seen attached Cerithium taken by any other method. But 
accidents cannot always be guarded against, and the objection 
to this system is that one’s whole stock of beakers is soon 
disposed of. An ordinary beaker holding about a gallon and 
a half makes a better and stronger examination tank than a 
vessel with parallel sides ; for although an object floats out 
of sight on either side, yet the condensation of the light 
along one side and the easy rotation of the water is very 
useful if the organisms searched for are small. 
When not in use the beaker is easily suspended from the 
roof of the cabin by a wire round its rim, and can thus swing 
in safety. 
However optically pure the sea water may appear under 
ordinary circumstances, yet a strong ray of light passed through 
it in one part will mark its track by myriads of minute specks, 
almost every one of them an independent organism, for there 
is little or no mere dust in the open sea. The water of 
course varies greatly in this respect at different times and 
places. The nearest approach to optical purity that I have 
come across is in the cold water that rises to the surface in 
patches off Cape Finisterre and its neighbourhood to the 
southward. 
About there, one dip may bring up water swarming with 
life—Diatoms in needles or spirals, or aggregated in gluti- 
nous masses, Thalassicollida, Noctiluea, Acanthometrina, 
Sagitta,and the Tunicates may be presentin abundance—and 
the next will be two or three degrees cooler and show nothing 
but a glancing diatomaceous needle and the inevitable 
