14 
POPULAR SCIENCE REVIEW. 
are formed by two glands found in the eighth ring of the body 
(figs. 7 and 5 b) ; they present a most beautiful structure, being 
composed apparently of polygonal cells : in their interior are 
found little vermiform bodies which assist in the secretion of 
the fluid that forms the egg-capsules. The eggs are probably 
deposited by a spontaneous dehiscence or rapture of the body, 
there being no natural outlet. Fig. 9 represents a (probably) 
secretory organ met with in the ninth ring of the body. Its 
function is not known. 
Whilst speaking of the circulatory system we should have 
mentioned that the general cavity of the body is filled with a 
fluid which surrounds all the internal organs. It contains 
numerous small granules of various sizes, very similar in appear- 
ance to those found in the quasi liver enveloping the intestine 
(fig. 1 5) . This liquid is probably merely pure water which brings 
the needful oxygen to the capillaries of the Tubifex, and answers 
the purposes of respiration. Such an arrangement is met with 
in many annelides, and is known as the chylaqueous system. 
Our little Tubifex not only presents us with a wide field 
for study and amusement in the investigation of its ana- 
tomy, but it actually forms the habitat of at least two very 
interesting forms of animal life. One of these is met with in 
the interior, the other attached to the exterior of the body. 
The animalcule which resides in the interior of the Tubifex is a 
species of Opalina ; it is very minute, and is covered by spiral 
rows of cilia, giving it, when in motion, an extremly beautiful 
appearance. It is one of the lowest forms of animal life belong- 
ing to Ehrenberg’s class Infusoria. The other parasite which 
we have met with in studying the Tubifex is the beautiful Vor- 
ticella. W e have examined but few specimens without finding a 
cluster of these exquisite living forms attached to the head or tail 
of the worm. The Vorticella, like the Opalina, is very low in the 
scale of creation, but it is of an entirely different form : sup- 
ported by contractile stems there are numerous cup or bell- 
sliaped bodies fringed round then margins with beautiful cilia. 
Thus it will be seen that even in localities and substances 
which are repulsive to the ordinary mind, the inquiring student 
may find living forms of intricate structure performing com- 
plicated natural functions, and affording a habitat for still 
simpler but equally interesting forms of life. Even this im- 
perfect and cursory review of the anatomy of the little Tubifex 
cannot fail to have afforded confirmation of the great truth, that 
all things are created in wisdom, and we may once more repeat 
that not only is it possible for the thoughtful man to read 
“ sermons in stones/’ and find “ books in running brooks,” but 
that even the muddy bed of a broad river yields its volumes for 
the edification of the inquiring mind. 
