v/ind often is the most important. This preeminence in deter- 

 mining the direction of the flow in the mouth of the Calcasieu river, 

 is due partly to the strength of the winds there prevailing, and 

 partly to the physical geography of the region. Calcasieu Pass 

 connects two l^rge bodies of shallow water, Calcasieu Lake and 

 the Gulf of Mexico. . In Lake Calcasieu the average depth is 12 

 feet. The Gulf near the pass is also very shallow for about half 

 a mile from shore and it is necessary to go out three miles to draw 

 27 feet. The hold of the wind on such shallow water is very great 

 and the currents which it produces gain such momentum as they 

 are forced through the narrow pass from one end to the other that 

 they are able frequently to obliterate the combined effects of the 

 river and tidal currents. 



But the direction of the wind is unsteady, and though it prevails 

 in different directions at different times of the year, during the 

 present summer there were several shifts often on the same day. 

 These changes of direction do not appear on the records of the 

 Weather Bureau because the wind is recorded but once daily at 

 six o'clock. But this makes no difference to the wind ; its effects 

 are not lessened, and may in determining the size of a set be very 

 great. The frequent shifts and their ability to change the direc- 

 tion of the flow in the pass so that the "tide" rises when it is ex- 

 pected to fall, or falls when it is expected to rise, or rises for a 

 brief time and then falls again, or vice versa, prevent the free 

 swimming young oysters from escaping periodically into the Gulf. 

 Indeed conditions often conspire to hold the free swimming larvae 

 in the pass and at such times suitable cultch is certain to secure 

 a set.* 



Two other results of this experiment deserve mention. The 

 value of clean shells as spat collectors is proven beyond doubt.' 

 This fact is by no means new but its importance is not always 

 recognized in localities wher;e oyster culture is not practiced. A 

 comparison of the new growth of the natural reefs and the spat 

 on the shells of the experimental ridges brings out in striking con- 

 trast the difference between old shells and clean cultch. The shells 

 on the reefs caught per hundred on an average 183 spat, whereas 

 those on the ridge parallel with the current caught per hundred 

 over 4000 and those on the ridge perpendicular to the current over 

 6000. That cleanness is largely responsible for this set is further 



*The possible importance of such bankings of the contents of the pass waspot. 

 recognized until the results of this expoi-iment wpre secured. In ronsoqiience no 

 careful records were kept. Such "banking up," however, did occur a number. 9fi 

 times between July 28th and September 1st. 



