Abstract
The use of ferricyanide in the presence of Cu++ to capture the ferrocyanide generated proved a reliable method for the location of succinic dehydrogenase in fern egg cells. The response of mitochondria-like nuclear evaginations was largely negative, but small patches of apparently authentic reaction product, absent in the controls, were occasionally encountered in their envelopes. From the point of view of deciding the nature of the nuclear evaginations the results were therefore equivocal.