May 31, 1901.] 
dwell in total darkness and be illuminated 
at times merely by the movements of abyssal 
fishes through the forests of phosphorescent 
aleyonarians.”’ 
Many authors have noted the light- 
emitting powers of numerous hydroids. 
These occur in great quantities over cer- 
tain areas of the sea bottom, and must add 
considerably to the sum total of deep-sea 
light. 
It may, I think, be said that in general 
the fixed marine forms are not behind their 
free swimming allies in either the equality 
or the quantity of their light-emitting 
powers. The question now arises, of what 
value is the phosphorescence of fixed forms 
to its possessors? ‘They have no eyes, and 
therefore can not be guided to their food by 
the light, neither can it aid them in find- 
ing mates nor in revealing the presence of 
enemies. Perhaps the most generally ac- 
cepted explanation is that given by Pro- 
fessor Verrill, who says that the phos- 
phorescence protects its possessors. Most 
celenterates, he says, are possessed of 
nematocysts or nettling cells, and the 
phosphorescence may serve to give notice 
to predaceous fishes that feed largely on 
hydroids, etc., that these nettling cells are 
present, and thus induce them to seek 
other provender. It is somewhat unfortu- 
nate for this argument that few if any of 
the ccelenterates that are remarkable for 
their phosphorescence possess nettling cells 
that are likely to be regarded by a hungry 
fish as at all formidable. 
Another explanation is, however, pos- 
Sible. The food of the cclenterates con- 
sists mainly of either crustacea of the 
smaller sorts, their embryos, protozoans, 
or unicellular plants. Now most of the 
crustacea have functional eyes, and it has 
been repeatedly demonstrated that they 
are attracted by light, both artifical 
and natural. Crustacean embryos usually 
have eyes that are proportionally very 
SCIENCE. 
851 
large. In many cases these too are at- 
tracted by light, and it is reasonable to 
suppose that they are attracted by phos- 
phorescent light. If this is true, the light 
emitted by the fixed cclenterates would 
cause the small crustaceans, and more 
surely their embryos, to congregrate near 
the illuminated areas and thus be captured. 
The process would be analogous, perhaps, 
to what is known as the effect of alluring 
coloration among insects and birds. The 
phosphorescence would thus be of direct 
utility to the fixed ccelenterates in securing 
food. 
The application of this idea may be still 
further extended to include the attraction 
of Protozoa and even diatoms, both of 
which groups contain many species that are 
strongly attracted by light, which appears 
to act as a direct stimulus to both unicel- 
lular animals and plants by virtue of its 
well-known effect upon protoplasm itself. 
One other fact, bearing directly on our dis- 
cussion, that impresses itself strongly upon 
every one who has had actual experience in 
deep-water dredging, is the very uneven 
distribution of life over the sea bottom. In 
other words, the distribution is ‘ spotted.’ 
A haul over certain areas will result in a 
dredge full of a profusion of animal forms, 
while the immediately adjacent bottom, al- 
though of apparently identical nature, will 
yield practically nothing. Our party re- 
peatedly observed this while dredging on 
the Pourtales Plateau. It seemed as if 
species were distributed in densely crowded 
colonies of very limited areas. Sometimes 
one particular species seems to have fairly 
carpeted the bottom, and in other localities 
a great assemblage of species would be se- 
cured at a single haul, showing a profusion 
of life, perhaps greater than can be found 
on a similar area either in shallow water or 
onland. Again the tangles would come up 
with nothing but sand and bottom débris. 
It seems, then, that we are justified in 
