ANIMALCULE ALLIED TO NOTOMMATA. 
335 
I have said that the body of the animal is filled with fluid, most probably analo- 
gous to blood, while the ciliated tags, or appendices, in perpetual motion, must 
produce currents in this fluid, and probably in an uniform and determinate direction. 
In this way the nutrient plasma will be brought regularly in contact with all parts of 
the interior of the body, and the process of nutrition go on as in insects, without the 
intervention of tubular vessels, the dorsal heart in them serving only to give direction 
and circulation to the blood. I am the more impressed with this belief, since these 
filamentous organs are in close approximation with a large contractile sac, presently 
to be described, which probably performs a respiratory function. 
As, however, this is a much-disputed part of the organization of the family of Hy- 
datinese, I shall here quote Ehrenberg’s own observations upon Hydatina Senta, 
which he takes as the type of the whole family. # 
“ It happened to me in 1832 to obtain a clear view of the vibratory corpuscles 
which CoRTi in 1794 saw, and doubtingly considered to be four hearts. I found 
here eight of these bodies, four on each side in two rows affixed to the sexual glands. 
In other Rotifera I saw many more of the same kind ; and in Notommata Syrinx and 
claviculata, a larger vessel was attached to the free and separated glands. These 
vibrating corpuscles are small and pear-shaped, free at one extremity and attached at 
the other, on all sides like little shaking purses, which either have on them a longer 
spiral coil, or within them four small separate vibrating folds, which are not under 
the volition of the animal. One only sees them clearly when the animal is flattened 
by the superimposition of a very thin light plate of glass, not crushing them. In 
Hydatina these vibrating valves or folds appear to be placed within the little purses. 
In Notommata collaris I have lately seen something prominent on their edges, and 
must therefore believe these folds to be placed on the outside. Besides, there appears 
in the neck of Hydatina to be present an opening in direct and important connexion 
with these organs, that in many other Rotifera projects as a spur-shaped horn. Close 
round this opening are placed the nerve-loops of the neck, and a nerve-ring appears 
to encircle it as a ganglion. 
The animalcule appears to take in, and expel alternately, clear water through 
this opening in the neck, and thus each vibrating organ throughout may be an internal 
gill producing respiration, although a circulation of the nutrient fluid (safte), partly 
on account of the extremely small diameters of the vessels, and partly from the 
transparency and minuteness of the blood-corpuscles, remains as yet undiscovered, 
though probably not deficient. Many of the older, as well as more recent observers, 
who speak of a heart in Rotifera, mistook the pharynx for this organ. Corti took 
the moving jaws and gills for it ; moreover, while no true heart has been discovered 
hitherto, it is impossible that it should hereafter be found to exist, especially as no 
congenerous animalcules have one, although by the tremulous motions of the vascular 
partitions {gefdsswande) the circulation of the blood is carried on.” — Ehrenberg, 
page 415, fol. edit. 1838. 
2x2 
