46 OYSTER CULTURE EXPERIMENTS IN LOUISIANA. 



ganisms, especially the minute plants known as " diatoms," on which 

 the oyster feeds, live habitually on or close to the bottom, from 

 which they are lifted and transported mainly through the agency 

 of waves and currents. Many of them possess feeble powers of 

 locomotion, but these are practically negligible in most of the bottom- 

 dwelling species. It is therefore obvious that when the water is 

 agitated by heavy winds and the bottom is stirred, the food organ- 

 isms which in calm weather lie more or less quiescent on the mud 

 will become mingled with other sedimentary matter in suspension 

 in the water and the quantity taken in the specimen will be vastly 

 augmented. This accords with field observation and is confirmed by 

 the correlation existing between the volume of the food and that of 

 the sand and other sedimentary matter in the precipitate from the 

 water specimens. "VMien the food is much in excess of the average, 

 ordinary sediment is likewise large in volume, and when it is at the 

 minimum, inorganic matter is comparatively lacking. 



At present there appears to be no accurate method by which these 

 fluctuations in the sedimentary condition of the water may be taken 

 into account in the study of the comparative values of different locali- 

 ties for purposes of oyster culture, the most that can be done being 

 to indicate more or less indefinitely the general state of the weather 

 at and immediately preceding the time at which the observations 

 are made. If observations could be taken at each locality daily or 

 at frequent intervals throughout the year, the average results at- 

 tained in different places would be strictly comparable, for the 

 methods employed show the quantity of food which is actually avail- 

 able to the oysters at the time of observation. 



AVhen the diatoms and other food organisms are lifted from the 

 bottom through the mechanical effect of the waves it is almost cer- 

 tain that the oysters should profit. Therefore, although we have as 

 yet no experimental data which would render the statement positive, 

 it is extremely probable that the matter of wave action must be added 

 to the numerous other factors entering into the food supply of oys- 

 ters, and that a certain amount of agitation of the bottom favors 

 fattening. A region subject to this phenomenon should accordingly 

 be preferable to one not so subject, and a season of strong winds 

 should be more favorable than one of prevailing calms or breezes so 

 light as to leave the bottom wholly undisturbed. When we have 

 accumulated more data on the subject it is not improbable that in 

 some cases seasons in which oysters fail to fatten may be found to 

 be characterized by the prevalence of light winds. 



During the course of the experiments in oyster culture previously 

 described an attempt was made to study the distribution of oyster 

 food on the coast of Louisiana in the hope that facts could be gar- 

 nered which would throw some light on the reasons for local and 



