Seaweeds and Leaf-green 
and so baffles its enemy. The light would probably be 
just as effective as the searchlights used in the Russo- 
Japanese war. 
A curious experiment has been recorded which may 
yet have a practical application. 
One fills an ordinary tumbler one-third full of alcohol 
(this is more than three-fingers or a third mate’s peg, as 
it is sometimes described), and then adds as much sea- 
water with pyrocystis in it as it will hold. 
If one then gently shakes or jars the tumbler, the 
pyrocystis glow with most unusual brilliancy for a time, 
not exceeding four minutes; they then sink to the 
bottom of the tumbler and remain very quiet indeed for 
a very lengthened period ! 
One must imagine not only these few plankton algz 
which we have mentioned, but many others developing 
regularly their one or two harvests, and being greedily 
devoured by many varied and remarkable marine free- 
swimming animals. 
There are also the beautiful submarine meadows and 
thickets of the shore algz. 
The world of fishes feed upon the smaller animals 
which graze upon the diatoms and other planktons. 
In fresh-water lakes one finds almost as varied and 
quite as beautiful a series of alge. There are both shore 
forms and free-swimming plankton. 
In the South of Scotland, the entire bed of a small burn 
or pond, every submerged stem of pond-weed, and every 
pebble may be covered with a curious golden-brown 
or dark brown mistiness. 
One finds under the microscope that this is due to 
small diatoms attached by delicate and almost trans- 
parent threads of jelly, and which, when observed in 
their natural condition, are exceedingly beautiful. They 
also have regular seasons of development; some appear 
39 
