. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ACTIVATION OF UNFERTILIZED STARFISH EGGS. 103 as the rectangular vessel and connecting the latter with the electrode dishes. These bridges were made as follows: A concen- trated solution of agar-agar in sea-water was allowed to solidify in a large beaker; the mass of jelly was then removed and cut into two blocks of the general shape indicated in the figure; one end of each block stood in the ZnSO4 solution and the other in the sea- water, as shown diagrammatically in the longitudinal section (Fig. i). By means of this arran
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ACTIVATION OF UNFERTILIZED STARFISH EGGS. 103 as the rectangular vessel and connecting the latter with the electrode dishes. These bridges were made as follows: A concen- trated solution of agar-agar in sea-water was allowed to solidify in a large beaker; the mass of jelly was then removed and cut into two blocks of the general shape indicated in the figure; one end of each block stood in the ZnSO4 solution and the other in the sea- water, as shown diagrammatically in the longitudinal section (Fig. i). By means of this arrangement strong currents (up to 2. FIG. i. or more amperes) could be passed through the sea-water. Ex- periment showed that the composition of the sea-water was not appreciably affected during the flow of the current for the period of an experiment. The temperature, however, rose rapidly unless controlled. In part of our experiments the control of temperature was effected by setting the whole system in a pan of ice water; this method proved satisfactory with currents of moderate in- tensity (up to 150 ).1 In a number of experiments with stronger currents another method was used, to be described below. The strength of the current was regulated by two rheostats and measured directly by a Weston voltmeter provided with shunts so as to read as a milliammeter over the several ranges required. Intensities as high as 3 or 4 amperes were used for a brief period in some of the experiments with running sea-water described below (densities up to ca. 800 ). The usual procedure was as follows: A somewhat small quantity of eggs was placed with a pipette in the rectangular dish midway between the agar bridges (2 to 4 cm. from each). When the eggs had settled the circuit was closed, and at stated intervals, usually 2, 4, 8 and 12 minutes, successive portions of eggs were transferred to small dishes (usually Syracuse watch glasses or stender dishes) 1 Milliamperes per square centime
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
