416 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1941 



tude and in 40° W. of Greenwich which appears to occupy the same 

 position today that it did in the time of Columbus. Between this 

 bank and the American shores, there are various smaller areas and 

 detached masses of this seaweed which are thrown into the ocean by 

 the eddies caused by the subcircular motion of the great ocean currents. 

 Humboldt computed that the whole of this area of seaweed in the ocean 

 covered about 260,000 square miles, but not all this space is completely 

 occupied with the floating seaweed. In many places there are spaces 

 of clear water between distant and narrow ridges of the seaweed. 



The geographical range of the Fucaceae is very extensive. It is 

 found on the eastern shores of Europe and on the western shores of the 

 American continent and in great abundance also off the shores of Japan 

 and China. Later, we shall study more fully the economic impor- 

 tance which it has in industrial life. It is thought that it probably 

 originated in rocks off the southern reefs and keys, where it was torn 

 by the storms from the rocks and as it floated about in the ocean con- 

 tinued growth from its broken parts. 



The giant kelp, as it is called on the Pacific coast, grows in such 

 great abundance that it sometimes forms natural breakwaters for 

 harbors, as at Santa Barbara, Calif. It also was greatly appreciated 

 by the early navigators since, when it grows close to the shore, it is 

 usually attached by holdfasts to large rocks so that mariners were 

 many times saved from shipwreck by the danger signals formed by 

 these large olive-brown floating seaweeds. 



ALGAE AS FOOD 



In the most primitive civilizations man is forced to seek from the 

 vegetable kingdom sources of food, especially in times when animals 

 are not plentiful. Since the earliest times, algae have been used by 

 man as food, especially as condiments, and a number of civilized 

 peoples still consume the seaweeds. 



The Chinese and the Japanese doubtless use a greater quantity of 

 seaweed as food than any other peoples, although the Hawaiians eat 

 it in large amounts. 



The beautiful livid purple gelatinous but firm membranaceous sea- 

 weed called Porphyra^ which is cosmopolitan in its growth, is one 

 of the most important food plants in Japan. It is consumed by every 

 class of the Japanese people and the cultivation of Porphyra is one 

 of Japan's leading industries. The Japanese call it amanori or laver 

 (pi. 2, fig. 1). It grows abundantly in bays and near the mouths of 

 rivers on all parts of the Japanese coast. Its cultivation was begun 

 at a very early date in Japan, and its financial returns, considering 

 the average yield per acre, are not surpassed by many branches of 

 Japanese agriculture. The earliest and most celebrated Porphyra 



