THE NEMATOCYSTS OF EOLIDS 
139 
nematocystes rejetes au dehors par la contraction des sacs. Cette atti- 
tude est done purement emotive, et n'a pas d'effet defensif direct. 
Ce n'est que lorsqu'on tracasse violemment 1' animal, ou mieux encore 
lorsque les papilles sont arrachees et comprimees, qu'il sort des sacs une 
masse de cellules nematophages et de nematocystes, qui explosent 
aussitot. II y a de tres bonnes raisons, tirees du mode de fonctionne- 
ment des nematocystes, pour croire que cette explosion non dirigee ne 
pent avoir qu'un effet insignifiant . . . ; mais laissons cela et essaj^ons 
des experiences." 
In combats with its own kind it is not surprising that the dorsal 
appendages should be attacked, for not only are eolids ''immune" 
to the nematocysts of the cerata, but these on stimulation are 
erected and project like the quills of a porcupine. The enemy 
comes unavoidably into contact with them. It is surprising, how- 
ever, to witness exactly the same thing when a blennie meets an 
eolid. If the blennie is hungry it behaves in a seemingly pugna- 
cious manner, darts at the eolid, seizes a mouth full of cerata, 
and pulls and twists them off as though they were tid-bits. As 
the blennie is one of the commonest denizens of regions inhabited 
by eolids we have here one instance at least, in which the 
defensive value of the nematocysts can be discounted. 
Many experiments with Fundulus heteroclitus were made. 
In general this fish, in the first trial of an experiment will take an 
eolid, but almost instantly regurgitates the captive. Contrary 
to my earlier statement ('06), a second or even third trial ma}^ 
be made, depending on the degree of hunger, and if the Fundulus 
is very hungry, the eolid may finally be swallowed permanentl}^ 
As the cerata are cast during these successive captures and regurgi- 
tations, it might be that the final retention is due to the loss 
of the nematocysts which at first rendered the eolid disagreeable. 
Further experimentation shows that this view is untenable, 
for if eolids completely devoid of cerata, or forms naturally without 
nettles are used, a fundulus will repeat all the performances 
which it goes through when dealing with a normal individual 
bearing nematocysts. Leaving aside altogether the nettleless 
nudibranchs, the eolids employed in these experiments were not 
