286 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



season than those planted in open, unconfined waters where cold cur- 

 rents interfere with the abundant development of food. 



This view is borne out by the fact that green-gilled oysters are in- 

 variably fat, and 1 are usually found at the end of summer in more or 

 less confined waters, or under such conditions as would obtain in in- 

 closed areas in some degree similar to the one used in our experiment 

 at Stockton. In truth, the writer is now continued in the belief that 

 the green-gilled condition is due to an abundance of green microscopic 

 food, which is absorbed in large quantities so as to tint the juices and 

 finally the blood-cells of the animal, and that these green organisms are 

 multiplied under just the conditions afforded by more or less com- 

 pletely inclosed ponds or areas of brackish water. 



THE REST COLLECTORS FOR MUDDY WATER. 



The collectors best adapted for waters which contain a large amount 

 of organic matter in suspension are evidently brush or stakes support- 

 ing strings of oyster shells strung on wire, because the tide will con- 

 stantly tend to sweep the accumulated sediment off the surfaces of the 

 twigs and shells. Such collectors should of course be put into the water 

 upright, so as to cause the collecting surfaces to be far above the bot- 

 tom, which is usually covered to a depth of from a few inches to several 

 feet with black ooze or mud in such situations. The brush should be 

 thrust with the main stem down into the mud far enough to support the 

 branched top against the tide, and also be so placed as to bring the top 

 below low water. The stakes, with their load of shells, should be ar- 

 ranged in a similar way. 



These two forms of collectors seem to me to be the cheapest and most 

 available in the practical work of spat collecting where the water con- 

 tains much sediment and the bottom is too deeply covered with ooze to 

 make shell planting profitable. Where the ooze is too deep shells will 

 rapidly sink into it so as to be entirely covered, and afford no surface 

 to which young spat can attach itself and grow. 



By means of some such method a large area can be rendered profit- 

 able as planting ground which is now utterly barren and useless for 

 such purposes. 



These are mere suggestions, but I am fully convinced from the facts 

 which have come under my observation during the last three years that 

 they are very important ones, because in many cases it is evident that 

 all that is needed to get spat is to afford surfaces upon which it may 

 attach itself in those situations where the bottom is deeply covered 

 with mud and where the fixation of spat and the establishment of oys- 

 ter-beds is often, without such provision, a sheer impossibility. The im- 

 portance of placing collectors in such places must, therefore, be evident 

 to the intelligence of the most ordinary person. 



