. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 88 S. H. CHUANG The tracing in Figure 1A shows a spell of regular peristalsis at the rate of about three per minute, while Figure IB shows some irregular peristaltic movements oc- curring in another specimen. A series of peristalses is usually succeeded by a rest period of variable duration. Hall (1931) showed that the oxygen consumption of Urechis in U-tubes bore no consistent relation to oxygen partial pressure at least over the range of to mm. Hg. The range of oxygen tension encountered by Ochetostoma in nature
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 88 S. H. CHUANG The tracing in Figure 1A shows a spell of regular peristalsis at the rate of about three per minute, while Figure IB shows some irregular peristaltic movements oc- curring in another specimen. A series of peristalses is usually succeeded by a rest period of variable duration. Hall (1931) showed that the oxygen consumption of Urechis in U-tubes bore no consistent relation to oxygen partial pressure at least over the range of to mm. Hg. The range of oxygen tension encountered by Ochetostoma in nature must be considerable from flood tide to ebb tide. Under experimental conditions the range of to cc. oxygen per liter at the onset of the experiments is within the usual range encountered by the animals and the experiments were continued. FIGURE 1. Record of peristaltic movements of Ochetostoma erythrogrammon. Read from left to right. Time : one division per minute. Each convex (upward) part of the curve repre- sents the passage of a peristaltic wave along the trunk. A. Record of a specimen with regular peristaltic movements. B. Record of another specimen with peristaltic movements occurring at irregular intervals. until the oxygen consumed amounted to about 25c/c of the original amount except in specimen 12 where the experiment was continued until the oxygen content dropped to In this case the consumption was not far below the mean, indicat- ing that a fall in oxygen tension did not materially affect oxygen uptake. In Table I the blocked anus of specimens 1-8 was released at the start of the second period. In specimens 9-12 the anus was blocked at the start of the second period. With the exception of specimens 8 and 9, the rate of oxygen uptake was greater during the second period irrespective of the state of the anus and the oxygen tension. Since Hall (1931) showed that the oxygen consumption in Urechis caupo almost doubled with increased activity, pr
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
