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10. 
11 
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Papers from the Department of Marine Biology. 
SUMMARY. 
. Individual differences in the responses of crinoids to the various 
kinds of stimuli indicate a complex nervous mechanism and 
forbid any simple explanation of their reactions. 
. Important differences in the methods of locomotion and of 
feeding show that different groups of comatulids (genera, 
families, orders, etc.) may give quite different responses to 
identical stimuli. 
. Many comatulids, especially the large multibrachiate species, 
are very sluggish, and the members of the family Comas- 
teride do not swim, but only creep about by use of the arms. 
. Comatulids of the families Stephanometride, Mariametride, 
Colobometride, and Antedonide, although ordinarily inactive, 
are good swimmers and do not creep as the usual method of 
locomotion. 
. It is doubtful if, under unchanged conditions, comatulids move 
about to any important extent, but it is certain that local 
changes can, and do, bring about considerable alteration of 
position and possibly real migrations. 
. Comatulids at Maér during the dry season are almost exclusively 
vegetable feeders, although protozoans form a small part of 
their nourishment. The food is not ingested as dead matter, 
but is unquestionably taken in as living material. Feeding 
is presumably accomplished by means of the ciliated furrows, 
and movements of the arms are certainly not essential and 
probably are not a very important factor. 
. All the comatulids at Maér are negatively phototactic. Brightly 
lighted areas are avoided and shadowed or dark places are 
sought. 
. The comatulids at Maér show marked susceptibility to heat and 
an increase of only 2 degrees produces an evident effect. 
Areas of markedly increased temperature are avoided. 
. The comatulids of Maér showed no response to a marked decrease 
in the salinity of the water and none to a slight increase of 
the salts. Their reaction to strong solutions of MgSO, is 
noticeably different from that of other echinoderms. 
Reactions to strong alcohol or formalin are marked and well 
defined, and normally follow a regular sequence. 
Reactions to impure sea-water, presumably to the CO, contained 
in it, are slow but sure. An excess of impurity soon produces 
inaction, followed ultimately by complete disintegration. 
