SENSES OF THE TUNICATA. 327 
guished poets of Germany. The Salpze progress by the alternate 
contractions and dilatations of their tubular body. In this 
manner the chains, as if obeying a common impulse, glide 
along with a serpentine movement, and are often regarded by 
sailors as sea-snakes. 
Before quitting the Tunicata, a few points of interest in their 
simple history remain to be noticed. Despite their humble 
organisation, they have a heart which, as may easily be ascer- 
tained in the transparent species, is subject to strange alter- 
nations of action. For after having received for a minute or 
two the blood from the branchiz, and propelled it to the 
system at large, it will at once cease to pulsate for a moment 
or two, and then propel the 
blood to the branchial sac, 
recelving it at the same 
time from the system gene- 
rally. After this reversed 
course has continued for 
some time, another pause 
occurs, and the first course 
is resumed. It is very pro- 
bable that many of the 
Tunicata are able to hear 
aud to see. In Chelyosoma, 
organs have been discovered 
whose structure seems to 
indicate that they are des- 
tined for the transmission 
of sound, and the Ascidie 
have frequently around the 
extremity of their tubes a 
5 ._.. Inner or under side of the superior plated 
row of coloured points simi- surface of Chelyosoma Macleayanum. 
. H fe os a. Branchial orifice. 6. Anal orifice. 
lar to the imperfect organs  ¢. Muscles bordering the carapace-plates. 
: 7 : d@. Central hexagonal plate. e. Surrounding plates. 
of sight present in the ma- f. The nerve-ganglion and nerve-fibres. 
A 2 - h. Auditory apparatus. 
jority of the bivalve Acepha- e Row of Centanles, anterior to the cesopnagus. 
: Jj. Stomach. 4%. Part of the intestine. 
lans. Thus a closer exami- 
nation of the lower animals is constantly bringing new faculties 
to light, and the further we penetrate into the secrets of their 
life the more we find occasion to admire the power and wisdom 
of their Maker ! 
Z2 
