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Journal of Experimental Biology 10,79-87 (1933)
Published by Company of Biologists 1933

The Energy Sources in Ontogenesis : VII. The Respiratory Quotient of Developing Crustacean Embryos

JOSEPH NEEDHAM ¹

¹ Gonville and Caius College, Cambridge; Biochemical Laboratory, Cambridge.

1. Respiratory quotients of the developing embryos of the shore-crab, Carcinus moenas, have been measured at different stages of development by manometric technique.

2. In the cleavage stages, the R.Q. is approximately unity, but by the time the yolk has diminished to four-fifths of the diameter of the egg, it has fallen to 0.72. After this time there is a slow and long-continued rise, but the quotient does not exceed 0.83 by the time of hatching. The significance of these observations for our knowledge of the sources of energy used by developing embryos is pointed out in the text.

3. In the course of these observations, it was found that normal respiration and normal metabolism (in so far as it can be appraised by the respiratory quotient) can be carried on by Carcinus embryos at temperatures above the probable thermal death-point of the adults.

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