Abstract
The amt. of choline esterase was detd. by the pharmacological method for Amblystoma punctatum, Bufo terrestris, and Rana sphenocephala, up to and including the early swimming stage. Only the last named sp. showed a relatively large amt. of choline esterase present in the cleavage stages. All 3 spp. showed a significant increase in the amt. of this enzyme during the period of developing motility. The slow relaxation during the early motile stages is thought to be related, among other things, to the lower choline esterase content.