Seaweeds and Leaf-green 
bath on board ship, and the results are often exceedingly 
interesting. 
There is a strangeness about this invisible swarming 
life of the high seas which is very fascinating. The 
so-called “Trades dust,” of which samples were taken 
by Dr. Reinsch when going to Brazil, turned out to be 
one of these alge (Trichodesma Hildenbrandti forma 
atlantica). Another species found by Ehrenberg in 
the Gulf of Sinai is responsible for the redness of the 
Red Sea. There are purplish, yellow green, and brown 
forms of this alga. 
The most abundant are probably the diatoms which 
form an isolated group of very curious little one-cell 
alge. Each cell is enclosed in a little flinty case 
very strangely ornamented by artificial-looking dots 
and lines. Some are circular, others rectangular, some 
are torpedo-shaped, whilst others are quite indescribable 
without illustrations. 
These diatoms are as important to the harvest of the 
sea as the grasses are to man and his domestic animals, 
for it is upon diatoms that those minute animals feed 
who themselves supply cuttle-fishes, ordinary fishes, 
and whales with daily nourishment. 
There seems to be two crops of diatoms in most parts 
of the world, one in spring and the other in late summer, 
but on this very essential point our information is by 
no means clear. 
In Southern Newfoundland, at depths of 5000 to 
6000 metres (2500 to 3280 fathoms), there are extra- 
ordinary quantities of the dead shells of a circular form 
(Coscinodiscus radiatus). This is the place where the 
cold Labrador current mingles with the warm water of 
the Gulf Stream, and the consequence is a continual 
massacre of the diatoms which sink to the depths and 
are there forming the mud or clay of the bottom.2! 
37 
