Questions dealing with the problems of general metabolic activities during embryonic development have, until rather recently, been largely answered in terms of the activities of the egg as a whole and upon the definite assumption that such data are in themselves real indicators of the physiological conditions of the embryo or embryonic cells (Needham, '31). Exceptions to this general rule have been pointed out by Needham and need no further discussion here except to emphasize the fact that for eggs other than the hen's no quantitative data seem to exist. I n recent investigations in this laboratory the necessity of learning of the parts played by the individual constituents of the developing egg in an analysis of cellular activities has become of especial interest and the present paper embodies results obtained from such experiments. Observations have been confined to the egg, embryo and extra-embryonic structures of the grasshopper, M. differentialis. Some idea of the rather unique nature of this material for experimental purposes may be had by reference to previous publications (Bodine and Boell, '36).
Methods
The eggs used in all experiments were prepared and handled as previously pointed out (Bodine and Boell, '36), but with exceptions as noted below. All eggs were sterilized ology.