. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RESPIRATION OF SINGLE CLEAVING EGGS 195 Figure 7. By comparing his Figures 1 and 3 (1950c), the cell division in Urechis evidently did not correlate well with the cycling, but occurred as we have plotted it in Figure 7, one position seemingly contradicting the other. He also found pe- riodicity in a frog egg that did not divide, and hence considered that the extra oxygen consumption was not closely connected with the cytoplasmic cleavage. We have observed two 6\ purpuratus eggs that did not divide and these did not show any
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RESPIRATION OF SINGLE CLEAVING EGGS 195 Figure 7. By comparing his Figures 1 and 3 (1950c), the cell division in Urechis evidently did not correlate well with the cycling, but occurred as we have plotted it in Figure 7, one position seemingly contradicting the other. He also found pe- riodicity in a frog egg that did not divide, and hence considered that the extra oxygen consumption was not closely connected with the cytoplasmic cleavage. We have observed two 6\ purpuratus eggs that did not divide and these did not show any change in O, consumption at the time when they should have normally divided. INFLUENCE OF Low OXYGEN TENSION UPON THE RESPIRATORY RATE AND CLEAVAGE Experiments were made to find out to what extent lowering of the oxygen ten- sion during an experiment would influence the rate of oxygen consumption. For this purpose the water was saturated with air instead of oxygen, so that the egg would actually run itself out of oxygen. Figure 8 shows that the oxygen consump- tion keeps on at normal rate until the last one or two minutes, when it abruptly stops. If the egg uses 180 //,/tl/hour or 3 /x/xl/min., and uses up all of the oxygen, then the consumption would not start to drop until there are only 6 /u^l left. Six L CONSUMPTION 150 JOO T- —r. 10 20 Mitt U T E.±> MO 50 60 70 90 too no FIGURE 8. Oxygen consumption in single cells: experiments where the chamber water was charged with air instead of oxygen. At the sharp bend the cell has used up all of the oxygen. In the upper curve the oxygen ran out just as cell cleavage started. The cleavage continued without any oxygen consumption. The irregularities during this division are artifacts due to sticking of the pressure control, produced by the excitement of the operator. The position of each curve on the ordinate scale is Please note that these images are extracted from scanned page images that may have been digi
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
