52 BOTANICAL GAZETTE [JANUARY 
(Colocasia esculenta) in irrigated patches called “loi.” These are 
located on the lowlands and valley floors. Water is skilfully 
diverted from the mountain streams, and spread in a thin sheet over 
the loi. These tiny fields are each only a fraction of an acre in 
area, and many are only 20-30 ft. each way. The bottoms and 
low retaining embankments are composed of black volcanic allu- 
vium. The loi are not continuously under water, but are flooded 
only at certain stages in the development of the taro. In this way 
each loi is at one time a shallow pond 6—12 inches in depth, at 
another a sheet of very soft, water saturated mud, and at another a 
sheet of fairly compact mud. These loi are notable habitats for 
the various fresh water algae, which occur in great variety and 
luxuriance. The algae may be found, according to their specific 
habitats, either floating on the surface of the water, free swimming 
in the water, growing upon the muddy bottom, epiphytic upon the 
stems of aquatic plants, or growing along the moist margins of the 
embankments, near the water’s edge. 
In recent years many of the taro patches have been converted 
into rice fields by the Chinese. The general conditions of irrigation, 
so far as influencing the alga flora are concerned, are practically 
the same for the rice as for the taro. Luxuriant growths of many 
fresh water species may be found in the rice fields. Some of the 
representative species occurring in these situations are as follows: 
FLOATING AND FREE SWIMMING.—Chroococcus, Raphidium, Scenedesmus, 
Gloeothece, Aphanothece, Merismopodium, Xenococcus, Lyngbya, Anabaena, 
Scytonema, Hydrodictyon, Conferva, Ulothrix, Cladophora, Spirogyra, etc. 
EPIPHyric. Rove alte Coleochaete, etc. 
re BOTTOM OR MARGIN yngbya, Nostoc, Anabaena, Scytonema, Stigo- 
dlothrix, Rivularia, Or is Draparnaldia, Oedogonium, Bulbochaete, 
N Nitello, Chara, M ougeotia, Zygnema, etc. 
Ditches and flumes 
A habitat for many kinds of algae is the irrigation ditch or 
flume. The very general use in the islands of irrigation water for 
the raising of taro, rice, sugar cane, and other crops has led to the 
development of elaborate systems of ditches and flumes. The inner 
walls and margins of these water channels support a diversified 
algal flora, despite the intermittent nature of the water supply. 
Many of the flumes are constructed of rough wooden planking, 
