. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 41).! JOHN CARRUTHERSFERGUSON as ng. N per ml. per hour. In the second case, for digestive glands weighing gm., k was and A, Equilibrium levels for the two cases would occur at 18 and 14 jug. N per ml. fluid. One further calculation is useful. The constant k, which represents the frac- tion of material removed per unit of time, can again be used to estimate the turn- over time. For the non-ammonia nitrogen data, the turnover times of the two cases turn out to be and hours. As each of these exp
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 41).! JOHN CARRUTHERSFERGUSON as ng. N per ml. per hour. In the second case, for digestive glands weighing gm., k was and A, Equilibrium levels for the two cases would occur at 18 and 14 jug. N per ml. fluid. One further calculation is useful. The constant k, which represents the frac- tion of material removed per unit of time, can again be used to estimate the turn- over time. For the non-ammonia nitrogen data, the turnover times of the two cases turn out to be and hours. As each of these experiments involved a pair of digestive glands, or one-fifth the total complement, the data would suggest that in the animal the time required to exchange all the nitrogenous nutrients in the coelomic fluid would be one-fifth of this, or, to hour. Release of nitrogenous substances from inhibited digestive glands It has already been shown (Table IV) that the absorption of nutrients by the tissues of the starfish is probably an active process. To further confirm this, preparations containing pairs of digestive glands in sea water with 2 X 10~4 M sodium iodoacetate were sampled and the concentrations of total nitrogen de- termined. The results of two such experiments are presented in Figure 9. As expected, reabsorption was inhibited and the full movement of material into the medium could be observed. The rates of release were fairly constant— gm. N per nil. per hour for the first set of glands (wt. gm.) and for the second 50 40 O) IL 20 10. 01 23456 hours Appearance of Total N (Inhibited) FIGI-RE 9. The rate of release of nitrogenous substances from pairs of digestive glands placed in 10 nil. sea water containing 2 X 10~4 M sodium iodoacetate. The lines are the mean slopes of the two Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illust
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