30 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
in nearly every case a complex of shibi of many ages. Transplanted shibi, with 
oysters of one or two years’ growth, usually form the nucleus of the cluster, and 
around them are planted concentric rows, one, two, or three, of branched shibi, old 
and new, to the end that all ultimately bind or mat themselves into a living, springy, 
cone-shaped mass, well suited to resist currents or storms. (Tig- 25 and PI. 5. ) Such 
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Fig. 21. — Arrangement similar to fig. 20, but in oblique order, adapted to a somewhat more rapid current. 
toya are made, or remade, toward the end of each spawning season, i. e., during 
the end of August or early part of September. They are then pulled to pieces (in 
this work the rake shown in fig. 14 is used), and from each bamboo there are shaken 
and broken off the oysters which are least securely attached. During this process 
the shibi found to be still useful are put aside to form the nucleus of new toya; 
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Fig. 22. — Arrangement similar to fig. 20, but adapted to rapid current, rows of collectors separated 
by intervals of 8 or 10 feet. 
the gleanings, twigs, detached oysters, and all, are now raked up and carried to a 
third locality, the living grounds (ike-ba). Here in swifter current the debris washes 
away and the oysters remain, the shells usually becoming clean in the meanwhile. 
(c) The living ground, or ike-ba, of which a good example is pictured in plate 4, 
is generally located in a zone of deeper water. It has a clean, gravelly bottom, 
