OYSTERS AND METHODS OF OYSTER-CULTURE. 283 



which will be the reading of tlie scale nearest the point where the sur- 

 face of the water touches the stem. For purposes of oyster-culture the 

 finer graduations may be neglected. To show the specific gravity, the 

 number "1.0" should always be i)laced in front of the scale reading; 

 for example, if the surface of the water should stand opposite the scale 

 reading "15," the density would be 1.015. The test should be made 

 immediately after tlie water specimen has been collected and a reading 

 of the thermometer should be taken at the same time. 



For practical purj^oses on the oyster-beds, a bottle or jar not less than 

 10 inches deep may be used instead of the copper cup, and any ordinary 

 thermometer may be used for obtaining the temperature. The cheap, 

 wooden-cased instruments known as "bath thermometers" serve very 

 well, as they have no metal parts to be corroded by the salt water. In 

 most oyster regions the salinometer reading from 1.020 to 1.031 will 

 not be necessary, as the density on the oyster-beds rarely falls within 

 its range. 



The specimens of water should be from the bottom, or near it, and 

 may be conveniently obtained by the following rough method: An 

 empty jug or large bottle weighted and corked is lowered to the bottom 

 by means of a line. The cork is then pulled out by jerking on a cord 

 previously attached to it, the receptacle fills with a sample of water 

 from or near the bottom, and if hauled rapidly to the surface it answers 

 the practical purposes of more scientific and accurate apparatus. 



SILT, MUD, AND SUSPENDED MATTER. 



A bottom composed of soft mud, into which the young oysters would 

 sink and become stifled, is unfavorable to oyster- culture or to the de- 

 velopment of natural beds. If, however, hard objects are distributed 

 over the bottom they will become collectors of spat so long as the 

 surface remains clean and free from slime and sediment, and the 

 importance of having water containing as little sedimentary matter 

 as possible is manifest if it is desired to produce permanent beds or 

 catch the floating fry. 



Oysters will grow more rapidly on muddy bottoms, or in their vicinity, 

 than they will elsewhere, as such situations are usually more pro- 

 ductive of food materials. This food is in the form of suspended or 

 swimming organic particles, and, therefore, filtered water, or that which 

 is devoid of suspended matter of all kinds, lacks one of the essential 

 requirements of successful oyster-culture. The most desirable water 

 is that which contains an abundance of minute living particles with a 

 minimum of suspended inorganic matter. An organic slime, however, 

 such as rapidly forms on exposed surfaces in some localities, is as 

 ettectual in preventing fixation as is inorganic sediment. In many 

 places in Chesapeake Bay and in the bays on the ISTew Jersey coast the 

 sediment, as well as the bottom mud, is largely com^wsed of the finely 

 comminuted fragments of vegetable nuitter, seaweeds, etc., the rapid 

 deposit of which soon covers with a soft film the surface of all objects 



