THE ACEPHALOUS MOLLUSKS. 185 
these cils in motion appear like oval wheels delicately toothed, 
which continually revolve from left to right. This movement 
engenders minute wavelets, which cause a current of water to 
traverse the sac of the mollusk, carrying with it live and dead 
matter, upon which the creature exists. Thus these singular 
animals—as many others—breathe and eat by the agency of the 
same organs! 
According to some naturalists, the ascidie have eyes. They 
think that six or eight red spots which are disposed round the 
orifices, are visual organs. But this is very questionable, for what 
possible use could eyes be to a creature which cannot move, whose 
prey is brought to it, and whose whole existence is involuntary ? 
And yet we cannot tell of what sensations these mollusks are 
capable; they may have joys unknown to us—joys dependent 
upon the light of the sun, which struggles through the azure water 
down into the depths they inhabit. 
The larvee of the ascidiz are of course not fixed; they are not 
unlike tadpoles, having large heads and short tails. Swimming 
away from their parent as soon as they are born, for some little 
time they give way to a roving propensity ; but the chains of 
instinct are about them, and in due time they settle down in life. 
This, however strange it may appear, seems contrary to their 
inclination ; for, on watching the process of this transformation, it 
has been observed that the larva, having placed its head against 
a rock or any other solid. body—doubtless directed by instinct, 
but probably utterly unprepared for the result—becomes fixed. 
This is the sign for the metamorphosis to commence; the head 
enlarges and grows hollow, the tail—if we may be allowed the 
expression—is flourished in the air. But soon the flourishes give 
evident tokens of anything but pleasure, for the motion begins 
to grow so rapid that it is difficult to see the tail. The struggles 
of the little creature are perfectly frantic, but all effort is useless ; 
it is a fast-bound prisoner for life; and, in time, ceasing its vain 
endeavours, it resigns itself to its fate. The tail drops off, a thick 
coating grows round it, rootlets spread like anchors from the part 
by which it is attached, and completely fix it ; and thus, forgetting 
the roving propensities of its youth, the bichus settles down and 
becomes a staid member of marine society. 
