NITROGEN CONTENT AND DISTRIBUTION IN EGGS OF MELANOPLUS DIFFERENTIALIS DURING EMBRYONIC DEVELOPMENT

¹ From the Zoölogical Laboratory, State University of Iowa

The total nitrogen content of the egg of the grasshopper, Melanoplus differentialis, has been determined and also the changes in its distribution among shell, embryo, and yolk. The nitrogen content of the whole egg is constant while the embryo nitrogen increases at the expense of the yolk nitrogen. The changes in shell nitrogen correspond to the formation and digestion of the cuticle. No change occurs during diapause.

A basal metabolism curve is computed from the embryo nitrogen curve of this paper and the oxygen consumption curve of Boell and Bodine (1936) which shows that the oxygen consumption rate rises to 20 mm.³ O₂/mg. N at 5 days postdiapause and remains steady at that value. A similar curve is computed for the yolk. The metabolic rate is constant in the prediapause at a value of 1.8 mm.³ O₂/mg. N and in the postdiapause drops from a peak at 2 days to 0 at 10 days. Both curves show very low rates during diapause.