. Culture methods for invertebrate animals;. Invertebrates -- Cultures and culture media; Invertebrates -- Collection and preservation. 26 Marine Invertebrates H, f= G the other jars. As soon as the lowest level is reached (determined by the position of the short arm of the siphon) the system begins to fill up and the level in all the jars rises. The rate of flow of water may be regulated to obtain the desired tidal interval. This arrangement was first employed by H. F. Prytherch in a study of the effect of oil pollution on oysters (Galtsoff, Prytherch, et al., 1935). (See note 2 on p. 50.) Ci
. Culture methods for invertebrate animals;. Invertebrates -- Cultures and culture media; Invertebrates -- Collection and preservation. 26 Marine Invertebrates H, f= G the other jars. As soon as the lowest level is reached (determined by the position of the short arm of the siphon) the system begins to fill up and the level in all the jars rises. The rate of flow of water may be regulated to obtain the desired tidal interval. This arrangement was first employed by H. F. Prytherch in a study of the effect of oil pollution on oysters (Galtsoff, Prytherch, et al., 1935). (See note 2 on p. 50.) Circulation of water in a closed system. Many organisms may be maintained in a limited supply of seawater if the latter is kept in circu- lation and is systematically filtered. Various simple devices designed to meet these requirements are based on the use of an air pump. The following is the description of a simple but efficient device (Fig. 31) designed by Burch and Eakin which we copy from Science (1934). The pump (P) (Fig. 31) is made from a pyrex glass test-tube, 10 cm. high and cm. in diameter. A glass tube (A) 5 mm. in diameter is sealed to the side of the test-tube approximately 2 cm. from the mouth and then bent parallel with the test-tube. A similar glass (B) is sealed to the base of the test-tube. The pump is placed in an inverted position in the reservoir and an exceedingly small air current is permitted to enter the pump through the glass tube (A) at the side. The exact depth at which the pump will give a maximum efficiency may be determined by experi- mentation; however, the pump should be at least 15 cm. below the water level in the reservoir. (See note on p. 50.) Another method developed by Cleve (quoted from Hagmeier, 1933) is shown in figure 32. The bottom of a tank is covered with a thick layer of sand (sd) through which water is sucked into a funnel (F) forming the lower end of the siphon, and is emptied into a small tank filled with sand and charcoal (ch)
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