ss ae | 
| 
VERMES, ECHINODERMATA, CBLENTERATA, 
PROTOZOA. | 
In the case of the higher animals, and even in that of the Articulata and | 
Mollusca, it was possible to regard them from a definite point of view, affording 
certain general data, on which to classify them according to their structure and 
mode of life. When we descend however to the contemplation of the lower forms 
of animal life this possibility vanishes altogether. So numerous are the varieties 
and so heterogenous the forms met with, that each genus must be taken on its own | 
merits in order to obtain an idea of its organisation. We will now attempt to | 
describe the most important groups in a few words. 
The Worms, Vermes, may be subdivided into three orders, viz: Annelida, Nema- 
todes and Platyhelminthes. As a general characteristic of all the worm tribe we 
may instance the soft skin and the hairs or bristles with which it is beset. In | 
other respects however the different genera show the utmost possible variety. 
In the general system of Natural History the Annelida, or Articulated worms, | 
stand immediately below the Articulata proper. They are distinguished by their 
blood being of a red color, and are subdivided into two groups according to the 
presence or absence of hairs at each of the numerous segments into which the body 
is divided. In some genera there is only a single hair at each segment, in others 
there are two hairs, or even a tuft, and these varieties are known as ‘simple or 
double oar’. In these worms the mouth aperture is situated on the under side, | 
immediately behind the first ring, and constitutes the entrance to the intestine, | 
| which in several of the genera can be protruded like a trunk and used for burrowing 
| or for capturing their prey. The worms with bristles mostly live in the sea, respi- 
ration being carried on by means of gills. Some genera move about freely in the 
water, others take up their abode in calcareous tubes at the bottom, their food | 
consisting sometimes of animal, sometimes of vegetable substances. Organs of vision | 
are not present in all cases. The smooth-skinned worms live in fresh water, or 
appear as parasites in the bodies of fishes, crustacea or mussels. The leeches — which 
belong to this class — have several pairs of eyes, and are armed with a very sharp 
mouth. They feed exclusively on the blood of vertebrate animals. The Annelida 
are propagated by means of eggs, the bristled worms having to pass through a larva 
stage before arriving at their perfect form. — | 
The Nematodes, or round-bodied worms, are destitute of all articulation, although 
the head is in most cases plainly marked. They mostly live as parasites on plants 
° 
a 
_ 
i=] 
aS 
= 
@ 
a 
° 
Es 
© 
a 
° 
- 
rE) 
= 
= 
=) 
At 
_ 
i=] 
— 
a 
fa] 
— 
) 
Se 
Ey 
ro) 
a 
) 
=) 
n 
o 
cS 
= 
° 
a=) 
= 
03 
) 
Ss. 
oO 
i=] 
me 
7 
5 
°o 
et 
) 
= 
° 
co 
o 
Q. 
=] 
c 
la 
@ 
me 
=} 
= 
=a 
@ 
4 
be) 
pee 
@ 
= 
° 
sar) 
=] 
a 
a 
@ 
oe 
> 
= 
ze 
= ad 
S 
=) 
n 
as 
—_ 
~~ 
@ 
QO 
ro) 
n 
@ 
5 
<4 
ao 
—< 
ae 
a 
@ 
a} 
7] 
= 
@ 
° 
> 
-_s 
So 
iz) 
= 
oO 
i=) 
n 
@ 
(=) 
= 
= 
 — i 
ie] 
na 
oe 
