40 ZOOLOGY: R. P. COWLES Proc. N. A. S. 
nutritive efficiency, and that a ''standard" allowance of 1 gram protein 
per kilogram of body weight per day provides a margin of safety of from 
50 to 100% above the minimum amount actually required to maintain 
equilibrium. 
F'or growth and reproduction the amounts of protein required are rela- 
tively larger than for maintenance, and the selection of the protein is also 
of greater importance. 
The data of all of the experiments here considered are summarized, 
with fuller discussion and with citation of original sources, in a paper which 
is being offered for publication in the Journal of Biological Chemistry. 
THE TRANSPLANTING OF SEA ANEMONES BY HERMIT 
CRABS 
By R. p. Cowi^KS 
Dkpartmbnt of Zoology, Johns Hopkins University 
Communicated by H. S. Jennings, November 6, 1919 
It is'well known that hermit crabs inhabit the vacant shells of molluscs, 
that as they grow they change from smaller shells to shells of larger size 
and that hydroids, sea anemones and other animals are frequently at- 
tached to these' shells. Several observers have reported that they have 
seen hermit crabs remove sea anemones from their old habitations and 
transplant them on their new shells. Such observations are mentioned in 
a few zoological text-books but usually the treatment is such as to leave 
the impression that there is an element of doubt as to the occurrence of 
the habit. For this reason I shall describe the behavior of individuals 
belonging to two species of hermit crabs, Pagurus deformis and Pagurus 
asper, occurring in the sea about the Philippine Islands, which bear sea 
anemones on their shells (Dolidae, Strombidae, Cassis, etc.) and which 
transfer these animals when they change their shells. My observations 
are worthy of note since they were made in the presence of four co-workers 
(Dr. L. B. Griffin, Mr. Alvin Seale, Professor A. L. Day and Professor 
S. F. Light), and since the individuals of the species of hermits mentioned 
both usually carry two kinds of sea anemones, one, a species whose in- 
dividuals are large, the other, a species whose individuals are small, the 
former being fixed, as a rule, on the top of the shell and the latter generally 
on the under side near the protruding head of the hermit crab. 
The following account of the behavior of the hermit crabs and sea 
anemones with reference to one another is undoubtedly in harmony vv^ith 
what occurs in nature although it deals with observations made in the 
laboratory: A hermit inhabiting a shell bearing two large sea anemones 
on the upper surface and a small one in the mouth of the shell was placed 
