ZOOPHYTA ASCIDIOIDA. 
241 
creting follicles, and distinct oral, cardiac, pyloric, and anal ori- 
fices. The whole floats freely in a visceral cavity, the bound- 
aries of which are formed by the delicate transparent parietes 
of the animal ; the space between the alimentary canal and the 
parietes being occupied by a clear fluid, and by the muscles 
which act upon the animal.”* 
Let us now suppose that the polypes are in a state of extru- 
sion and fully expanded, as represented in Fig. 39, a ; all the cilia 
in play, and the water whirling in rapid streams up and down 
the opposite sides of the tentacula, carrying with them nutri- 
ment and the breath of life. All is quietness and security 
around, and the little creatures are evidently in a state of hap- 
piness and enjoyment : no one who has witnessed the micro- 
scope scene, — the myriads of the little flosculous heads that 
pullulate and blossom over the entire polypidom, as thickly 
peopled as the swarming hive, can have any doubt of this,-f* es- 
pecially when he remarks the acuteness and vivacity of their 
sensibilities and actions, for, under his eye, one will ever and 
anon suddenly sink out of view, hide itself within the cell, again 
on a sudden emerge and expand, or, it may be, lay itself down 
in repose and concealment, until digestion has freed it from a 
state of repletion, or forgetfulness has removed the alarm of an 
enemy.J These positions are assumed with such a rapidity that 
the eye cannot trace the steps of the process ; and large glasses 
and minute skill are required to reveal to us its mechanism. 
* Farre in lib. cit. p. 393. 
t “ The heart is hard in nature, 
that is not pleased 
With sight of animals enjoying life, 
Nor feels their happiness augment his own.” 
Cowper. 
f “ No trace of either nerves or ganglia could be detected ; yet the attributes 
of a nervous system were so clearly exhibited as to leave no doubt but that this 
must exist, and probably in some degree of perfection. Not only was the deli- 
cacy of their sense of touch very strongly marked, but the operations also con- 
sequent upon the enj oyment of such a sense were sometimes singularly striking. 
This is seen in the instant retiring of the animal on the slightest alarm, and the 
caution which it sometimes shows before emerging again from its cell ; in the 
obvious selection of its food ; and in the pertinacity with which it refuses to ex- 
pose itself to water that has become in the least degree deteriorated .” — Farre in 
Phil. Trans, an. 1837, p. 414. 
9 
