USEFUL ALGAE — CHASE 4l5 



water (liquid) thus enabling them to tide over periods of drought 

 and to start growth as soon as wet weather begins; their successful 

 competition with higher plants during drought; and the fact that 

 after death they must form surface humus. The algae that grow 

 in the soil to a depth of 6 inches surely must enrich it with the 

 addition of organic material. 



Not all of the marine algae are small, ornamental, delicate sea 

 mosses or coarse, succulent, unattractive kelps or rockweeds, which 

 have in both cases little substance remaining after their decay. There 

 are many different kinds of marine plants that secrete lime from 

 the sea water and are more or less hard and stonelike, although they 

 form beautiful purple and lavender incrustations, so that their decay 

 or continued upward growth is accompanied by a considerable in- 

 crease in the height of the sea bottom where these plants are growing. 

 The corals (animals) are, generally speaking, confined to the tropi- 

 cal seas, but the corallines (lime-secreting seaweeds which have a 

 superficial resemblance to the corals) are more widely distributed. 

 The fact has been known for years that the corals and other lime- 

 secreting animals are active agents in building reefs and forming 

 land, but only recently has it been noted that certain marine algae 

 or seaweed, the corallines, have a function in the same great work. 

 Kjellman has stated that off the shores of Spitzbergen and Nova 

 Zembla LithotJiaranion glaciale, a coralline, forms thick layers on 

 the ocean floor at a depth of 60 to 120 feet in the water and that in 

 the future formation of the strata of the earth's crust in these re- 

 gions it will become of essential importance. Algae probably form 

 the largest mass of the shell sands of Bermuda. Sir John Murray, 

 in reporting the results of the famous Challenger expedition, has 

 recorded that in three out of four samples of so-called coral sand 

 or mud from Bermuda, over 50 percent of the mass has been com- 

 posed of the calcareous seaweeds and their broken-down parts. 

 Materials brought up by borings that were made to a depth of 1,100 

 feet in Funafiuti, a true coral island of the Ellica group, indicate 

 that the lime-secreting seaweeds have been of greater importance 

 than the corals in the formation of this island. 



Nature's provision of vast beds or groves of giant kelp of the genus 

 Sargassum of the order Fucaceae has been appreciated by voyagers 

 since the time of the Phoenicians. Aristotle speaks of the weedy 

 sea which they found at the termination of their voyage, and un- 

 doubtedly he was referring to the kelp. Columbus was the first 

 voyager of modern times (September 16, 1492) to encounter it but it 

 is possible that the same bank of seaweeds that he discovered was 

 the one found by the Phoenicians. A great bank of Sargassum 

 extends between the twentieth and forty-fifth parallels of north lati- 



