I HAVE read with considerable interest the recent communication from Dr. L. H. Hyman dealing with the water content of medusae1. My apologies are due to Dr. Hyman for having failed to refer to his communication of 19382 in my own contribution to NATURE3 ; but when I was doing the work and also when writing up the account it was impossible for me to get hold of the proper references, since the greater part of the library has been removed from the Laboratory at Plymouth. However, the omission shows the close agreement in our independent results.