226 
THE OCEAN WOULD. 
higher animals : tlie common trunk canal is thus formed, which 
directs itself to the stomach, receiving in its way thither all the 
lateral branches. 
A very distinct circulation exists in the Medusae. The peripheric 
part of the stomach suffers the nourishing liquid which has been 
elaborated in the digestive cavity to pass : this fluid then circulates 
through numerous canals, the existence of which have been clearly 
traced. 
It is also a singular fact, that organs of sense seem to have been 
discovered in these Medusae, which early observers believed to be alto- 
gether destitute of organization. “ During my sojourn on the banks 
of the lied Sea,” says Elirenberg, in his work on the Medusa aurittt , 
“ although I had many times examined the brownish bodies upon the 
edge of the disk of the Medusae, it is only in the month past that 1 
have recognised their true nature and function. Each of these bodies 
consists of a little yellow button, oval or cylindrical, fixed upon a thin 
peduncle. The peduncle is attached to a vesicle, in which the micro- 
scope reveals a glandular body, yellow when the light traverses it, but 
white when the light is only reflected on it. From this body issue 
two branches, which proceed towards the peduncle or base of the 
brown body up to the button or head. I have found that each of 
these small brown bodies presents a very distinct red point placed on 
the dorsal faco of the yellow head, and when I compare this with my 
other observations of similar red points in other animals, I find that 
they greatly resemble the eyes of the ltotifera and Entomostraca- 
The bifurcating body placed at the base of the brown spot appears to 
be a nervous ganglion, and its branches may be regarded as optm 
nerves. Each pedunculated eye presents upon its lower face a small 
yellow sac, in which are found, in greater or smaller numbers, small 
crystalline bodies clear as water.” The presence of a red pigment 1,1 
very fine grains is an argument in favour of the existence of visual 
organs in these zoophytes, for the small crystals disseminated in tlm 
interior of the organ would no doubt perform the part of refracting 
light which is produced by crystalline in the eyes of vertebrate! 
animals. Moreover, it is found that there are marginal corpuscle 9 
analogous to these brown spots in other species of Medusae. They 
are of a palish yellow, or quite colourless, and enclose sometimes a 
single, sometimes many calcareous corpuscles. When they are colour' 
