550 SUPPLEMENT 
As there are no appendages, it is evident that there can be 
no muscles for the purpose of moving them, though some in- 
distinct fasciculi may be observed in some of the exterior 
species. 
The apparatus of nutrition is also very simple in the 
entozoa. 
As for that of digestion, or the intestinal canal, it is gene- 
rally extended from one extremity to the other of the body, at 
least when it is complete. At other times it is irregular or 
ramified, and, finally, in a certain number of species it is 
vascular, or even sometimes completely imperceptible, or 
even nullified. 
When complete, it extends almost directly from one ex- 
tremity to the other, but never without being free or distinct, 
and consequently without any serous or peritoneal membrane. 
It is truly comprehended in the cellular parenchyma, which 
constitutes the mass of the body. 
The mouth, almost terminal, is almost constantly very 
small and circular. 
It is never armed with teeth, properly so called, whether 
calcareous or corneous. Sometimes certain projections, or 
swellings, of the muscular contractile tissue may be found, 
the edges of which bristle with remarkably fine denticu- 
lations. 
As there is no real armature of the anterior orifice of the 
intestinal canal, we may easily conceive that there never 
exists in these animals any distinct buccal mass. 
Neither are there any salivary glands. 
We may say, that in general, in the extent of the intestinal 
canal, there is no distinction of cesophagus, of stomach, pro- 
perly so called, of small intestine, and of rectum; such at 
least is the case in all the truly intestinal worms. 
No organs have been met with that could be regarded as a 
liver, and still less asa pancreas. If the first does exist, which 
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