ALGAE — MEIER 427 



upon algae as direct or indirect sources of the oils and vitamins of 

 their food and energy. In turn, through the game fishes, the algae 

 constitute indirect sources of food and energy for the human race. 

 One scientist studied the algae in 5 ponds by making a collection 

 and investigation of the intestinal contents of 100 tadpoles in each 

 pond at 4 different intervals during a year. At the same time the 

 tadpoles were collected, an equal number of pond collections were 

 made. From all the pond collections and tadpoles, 170 species of 

 algae were obtained. In every case except two (in these they were 

 equal), the number of species obtained from the tadpoles exceeded 

 those obtained from the pond collections. This was noticeably true 

 when the ponds involved were large. These results indicate that the 

 algae found in the intestinal tract of the tadpoles serve as a reliable 

 index to the algae of ponds from which the tadpoles were taken. 



On the Pacific Coast marine algae such as LaininaHa japonica are 

 used for the manufacture of iodine. Gelidvmn cartilaginewm is har- 

 vested on southern and Lower California shores and converted into 

 an improved and purified grade of agar at San Diego. The chemical 

 and physical properties of agar make it applicable to industrial use 

 as a thickener or jelly producer. It is used extensively as a culture 

 medium in bacteriological work, for sizing cloth, and to make candy, 

 breakfast foods, and fancy jellies. Agar is imported from Japan to 

 the United States in large quantities. The Japanese agar is made 

 from various species of GelidiuTn, Gracilaria, and Eucheuma. The 

 large kelps possess a high percentage of potassium salts, so that when 

 the foreign supply of potash was cut off during the World War, 

 several firms under Government subsidy harvested great quantities 

 of kelp and produced the needed chemicals, but with the end of the 

 war the business gradually declined. At the present time there are 

 two concerns using kelp in California. One of these produces chemi- 

 cals and fertilizer, the other makes products which are marketed for 

 human consumption, for stock feed, and for fertilizer. The four 

 species of kelp used commercially in California are Macrocystis 

 pyrifera^ Nereocystis luetkeana, Pelagophycus porra, and Alaria 

 fMulosa. 



As food for human consumption, seaweeds have long been in use in 

 various parts of the world. The Chinese and Japanese, in their con- 

 tinually losing race between their population and food supply, culti- 

 vate various forms of algae for food. The Chinese use a great deal 

 of seaweed, and for the past 40 years they have gathered seaweed on 

 the California coast for export to China. The only local seaweed 

 utilized directly as human food today is Porphyra perforata^ which is 

 found on the Pacific coast from the State of Washington to Mexico. 

 It also furnishes food for the abalone and the sea slue. 



