It is shown that equilibrium of 32P throughout the body of Calanus is reached only after a feeding period of about a week. The time required to liberate by excretion the amount of P present in a Calanus is about 20 days. Fed Calanus excrete at a higher rate than starved. The implications of excretion in feeding experiments using 32P is discussed.

There are large differences in the total P content of individual Calanus. Figures are given for ripe and unripe females, fat and lean Stage V, and eggs. A high percentage, up to 55% of the total P, may be lost by excretion during starvation.

A high proportion of the P in the food assimilated (up to 70%) may appear within a week as eggs laid.

Liberation of P from dead Calanus is very rapid and is almost complete in three days.

The relation of excretion and autolysis to the P cycle in the sea is discussed.