12 
POPULAR SCIENCE REVIEW. 
“ muscular membrane” envelops the whole body, in common 
with the skin, and attached to it are transverse muscles which 
constitute the boundaries, as it were, of the rings of the body. 
These muscles, by their contraction, impart to the little Tubifex 
its undulating and longitudinal movements, and a probable modi- 
fication of them is found in another set of muscles at the 
mouth of the animal, these latter being intended to regulate the 
movements of the pharynx (fig. 1 c). 
The reader will no doubt be somewhat surprised to hear that 
so diminutive an organism should be furnished with a compli- 
cated nervous system, perfectly adapted to its general structure, 
and for the fulfilment of its wants. 
A careful examination of the little annelide is necessary for 
the definition of the nervous system, which is found to resemble 
the other forms of this order. It consists of a long double 
cord of nervous fibre, which runs throughout the length of the 
worm, and gives off in each segment of the body three pairs of 
nerves, which direct the movements of the muscles bcloucino- to 
that ring. The points in the nervous cord whence these nerves 
spring are slightly enlarged, and are called “ganglia” (fig. 3). 
In the first ring of Tubifex we find a very large ganglion (fig. 
3,«),the two nervous cords enlarging into a round mass composed 
of nervous matter ; this represents the brain of higher animals, 
and from it spring two pairs of nerves, one of which is connected 
with an organ supposed to be the eye ; but of this there is great 
doubt. W e ourselves have tried several experiments to ascertain 
whether the Tubifex has been favoured with organs of sight or 
not, and have come to the conclusion that it is blind. The 
Creator has nowhere exercised his Almighty power uselessly, 
and eyes would certainly be of no use to our little annelide, as 
his food consists merely of the mud which he inhabits, from 
which all the nutritive matter is extracted in his intestinal canal. 
Strange though it may seem, the Tubifex is provided with a 
liver, and a very large one too, and is therefore liable, in com- 
mon with the human race, to bilious attacks. The intestine is 
covered throughout its length with a dark yellow membrane 
containing curious little granules (fig. 14), anc! capable of secret- 
ing and projecting a fluid into the intestine — this is the liver — 
and is no doubt most important in digesting such bonnes-bouches 
as Thames mud affords. 
The animalcule is also provided with excretory organs answer- 
ing to the Iddneys in higher animals — there are two in each 
ring of the body — consisting of little tubes until an internal and 
external opening covered internally with minute vibratile hairs 
or “ cilia,” which are also continued around the expanded 
orifices, as seen in fig. 6. When the Tubifex is placed under 
the microscope, these “cilia” may be seen in rapid motion, 
