. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 702 ERIK ZEUTHEN AND KIRSTEX HAMBURGER ting the bicarbonate (exp. B). At the end ( hours) of the measurements of A(Oo — CO.,)/At the flotation medium and diver's neck fluid were replaced with 2/100 N NaOH, so that measurements of AO2/At could be made between and 7 hours. The curves for A(O., ('().,)/At resemble those for AO2/At in that there is one wave per mitotic cycle and furrow formation comes at a time when the rate of gaseous exchange is iiu-re;using. However, these curves show more cyclicity as demonstrated by
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 702 ERIK ZEUTHEN AND KIRSTEX HAMBURGER ting the bicarbonate (exp. B). At the end ( hours) of the measurements of A(Oo — CO.,)/At the flotation medium and diver's neck fluid were replaced with 2/100 N NaOH, so that measurements of AO2/At could be made between and 7 hours. The curves for A(O., ('().,)/At resemble those for AO2/At in that there is one wave per mitotic cycle and furrow formation comes at a time when the rate of gaseous exchange is iiu-re;using. However, these curves show more cyclicity as demonstrated by Table I. Differences, to be read on the ordinates, between pairs of curves for ACX/At ( here dashed in at proper levels and in proper relation to the cleavage cycle) and A( O, — CO2)/At represent carbon dioxide liberated to the diver's gas space. en . cn 4 d. E 3 in o 2h X R4 1r- 0. B 0 hours FIGURE 3. Rates of carbon dioxide production fACO»/At) calculated on basis of the curves shown Figure 2. Arrows indicate when cleavages 1-5 (A) and 2-3 (B) begin. The total amount of carbon dioxide liberated by the egg was calculated on the basis of two assumptions: (1) The diver is tight to CO,, and (2) the total volume of water in the diver (always including the egg water) serves as a dis- solving space for CO2. These assumptions are discussed at length elsewhere (Hamburger and Zeuthen. in preparation) and seem to be justified. We first cal- culated , , CO., liberated to the diver's air space, as represented by the area, over a narrow segment of the abscissa, between curve A(O2 — CO2) At and the corresponding curve AO.,/At (dashed). The amount of CO2 liberated by the egg per unit time, ACO. At, approximates ACO,/At " ACO2Bir/At(k + 1), in which k is the ratio between water and air volumes in the diver times the absorption coefficient for CO2 in water at the temperature of the experiment; k is derived from linear measurements of the compartments of the diver. Fig
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