. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 314 RALPH D. LOWELL AND ALLISON L. BURNETT adjustable clamp for admitting the perfusate, a transparent chamber for monitoring flow rate, and a J-shaped piece of glass tubing which carries a specially perforated #33 hypodermic needle on its lower end (Fig. 2). A hole is made in the side of the needle with a fine grinding wheel about .', inch from the tip and the tip sealed with epoxy (Hysol 1C White). The hydra is threaded on the needle with the point entering the pore in the basal disc and coming out the mouth and the animal
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 314 RALPH D. LOWELL AND ALLISON L. BURNETT adjustable clamp for admitting the perfusate, a transparent chamber for monitoring flow rate, and a J-shaped piece of glass tubing which carries a specially perforated #33 hypodermic needle on its lower end (Fig. 2). A hole is made in the side of the needle with a fine grinding wheel about .', inch from the tip and the tip sealed with epoxy (Hysol 1C White). The hydra is threaded on the needle with the point entering the pore in the basal disc and coming out the mouth and the animal positioned so that the opening lies in the gastrovascular cavity. Since the hydra often works its way off the needle it is maintained in position by forcing a small piece of Parafilm over the needle tip ( Figs. 3 and 4 ). The needle together with the lower part of the perfusion unit is immersed in a dish of standard culture medium ( Loom is and Lenhoff, 1956) made up with distilled water. It is not necessary to maintain a specific rate of flow; the purpose of the monitoring chamber is to insure that flow does not stop from contraction of the animal around the needle. The temperature of the perfusion dishes was maintained between 10—15° C throughout the separation FIGURE 3. Hydra on perfusion needle showing epidermal separation. X 66. FIGURE 4. Hydra on perfusion needle showing spontaneous eversion. X 66. Separation is usually evident without the use of a microscope. Following separation the lower part of the perfusion unit, still immersed in its dish of culture medium and with the hydra still on the needle, is detached from the monitoring chamber and mounted in a clamp under a dissecting microscope. Iridectomy scissors and Xo. 5 watchmaker forceps are used for removing the epidermis. Once punctured, the separated epidermis tends to collapse inward, but by grasping the cut edge with the forceps it can be lifted away from the gastrodermis. Then by exerting gentle te
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
