IMPORTANCE 161 



of the bottom, the depth, and a number, beginning 

 with i, and so on. The numbers of the specimens 

 must also be entered in a notebook, wherein all details 

 are to be mentioned that strike the collector, such as 

 the different shades of colour which some algae have in 

 and out of the water, and the periods of the year in 

 which they occur ; for many algae have regular periods 

 of growth and rest just like the higher flowering plants. 



Utility of Algae. — The commercial value of algae is 

 relatively small. Formerly large quantities of Kelp 

 and Fuci were gathered, and even grown, on the coasts 

 of islands near Ireland and Scotland for the manufac- 

 turing of carbonate of soda. This was, however, after- 

 wards given up. Kelps are still collected for the 

 manufacture of iodine. Many algae are used as 

 manure, and in Northern Norway cows are fed in 

 winter-time on Rhodymenia palmata (Dulce), if other 

 fodder is scarce. In the Indian Archipelago and in 

 Japan various species of algae are consumed by the 

 people, and species of Eucheuma and Sphaerococcus 

 are the chief components of the famous agar-agar. 



The real importance of algae in oceanography lies 

 in the fact that they form the basis of the ultimate 

 food-supply of the neritic or coastal fauna. 



The original drawings which illustrate this section were made 

 under the author's direction by Mr. J. Obbes. 



ii 



