. Culture methods for invertebrate animals;. Invertebrates -- Cultures and culture media; Invertebrates -- Collection and preservation. i8 Marine Invertebrates. outlet through which the water is drawn from a storage tank is always located several inches above the bottom. A small amount of seawater may be made to last a long time if the investigator regularly filters and aerates it. A very convenient type of filter (Fig. 19) consists of a water- tight wooden box with two pipes passing through its bot- tom. The long pipe serves as an overflow while filtered water runs through a short pipe after
. Culture methods for invertebrate animals;. Invertebrates -- Cultures and culture media; Invertebrates -- Collection and preservation. i8 Marine Invertebrates. outlet through which the water is drawn from a storage tank is always located several inches above the bottom. A small amount of seawater may be made to last a long time if the investigator regularly filters and aerates it. A very convenient type of filter (Fig. 19) consists of a water- tight wooden box with two pipes passing through its bot- tom. The long pipe serves as an overflow while filtered water runs through a short pipe after having passed through a layer of charcoal (ch), sand (sd), fine gravel (fg) and coarse gravel (eg). From a reservoir (not shown in the figure) the water is delivered to the aqua- ria. When in operation the filter is placed below the aqua- rium from which the water is drawn. (See also p. 540-) Sometimes experimental work requires the use of seawater entirely devoid of any suspended matter, either inorganic or organic. It may be obtained by filtering through collodion membranes (ultrafiltration), using fine Berkefeld filters, or by passing through a thick layer of asbes- tos. Water obtained by the latter method may not be free from bacteria but contains no plankton or micro- plankton. A typical arrangement is shown in figure 20. From a labora- tory faucet seawater runs slowly into a large Buchner funnel, the bottom of which is covered with a layer of asbestos (A) about 1 inch thick. A small watch glass is. placed on its surface to provide a more uniform distribution of water over the entire area. The funnel is inserted into a neck of a 2 liter Fig. 19.—-Filter for seawater. After Sachs, eg, coarse gravel; ch, charcoal; fg, fine gravel; sd, sand. To suction pump. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.
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