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 tl Trades dust," of which samples were taken 

 by Dr. Reinsch when going to Brazil, turned out to be 

 one of these algae (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. 20 



The most abundant are probably the diatoms which 

 form an isolated group of very curious little one-cell 

 algae. 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. 21 



37 



