lar action. These effects may result from a decline in the intracellular sodium levels
but they could also be due to a decrease in the extracellular space of the muscle.
In another series of experiments CHESTER JONES et al. found that the extracellular
space decreased following the injection of extracts of Myxine pituitaries into these
fish. The site of such actions of the hormones is not clear.
The role of endocrines in the osmoregulation of the hagfishes seems to have
been neglected in recent years. With the more refined techniques that have become
available for measuring the permeability of fish it is high time that they received
the attention to which they are entitled. The hagfishes could be exhibiting osmoregulation like that of the first vertebrates, but even if this is not so, it is a pattern
that is unique among contemporary fishes .
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