Some Notes on Alcippe lampas (Hanc.). 183 
Leaving the others aside, I am inclined to take Alcippe as a 
regular messmate of the hermit-crab. As Avrivinirus points out, 
the animals are found only in shells inhabited by the crabs and 
they cannot be kept alive very long after the crab has been removed. 
The matter in the intestine of Alcippe is always extremely finely 
divided and while there is often a good deal of it which stains 
very readily esp. with haematoxyline, I have had no more luck in 
determining the nature of the food from my serial sections than 
Bernpt had with his. The animal evidently feeds on very finely 
distributed organic matter, be that fine particles which pass into 
the water when the crab cuts and prepares its food, be that faecal 
matter. The relation of Alcippe to the crab cannot be called 
parasitism, for it does not seem to rob the crab of its food or in 
any way of its energy, not even “Raumparasitismus”, for Alcippe 
does not occupy space which otherwise would be occupied by the 
crab. It is not in its way and even a strong increase in its number 
will hardly make the shell so brittle that the crab would have to 
seek a new one on that account. The weight which the crab has 
to move about is not increased either, on the contrary, the animal 
is lighter than the mass of calcareous substance which it replaces. 
Symbiosis, the name given by Avrtvintius to the peculiar 
companionship of crab and Alcippe, is as BERNDT rightly points out 
not applicable as long as the advantage to the crab cannot be de- 
monstrated; nor would mutualism do for similar reasons. Commen- 
salism seems to be the only term which fits the case. Of course, 
in itself this is a matter of no importance. What leads me to 
discuss it is not the satisfaction of putting a thing in a pigeon-hole 
and sticking a label to it, but rather the desire to call attention 
once more to one of those very interesting cases where one animal 
finds the conditions for its existence in the neighbourhood of another 
and apparently only there. We cannot always express these con- 
ditions by a simple formula such as parasitism, symbiosis and 
commensalism, they are evidently more complicated than we can, at 
present, demonstrate. . In cases where we have a clean shell in- 
habited by a crab and Alcippe, the relation seems simple. But these 
cases are rare. In such shells we find no or only very small 
specimens of Alcippe. More and more other guests establish them- 
Selves, until the whole forms a little world of its own. I am in- 
clined to believe that each member in this little world fills its place, 
has adapted its life to the peculiar conditions and thrives best under 
