404 ENTOZOA. 
coition ensues as among other animals. We are then compelled to 
believe, that they propagate their race by germs sufficiently minute 
to be transmitted through the narrowest passages, and that frequently 
those germs are contained in animals at birth. 
In the Intestinal worms we find neither trachez, nor any other 
organ of respiration, and they must receive the influence of oxygen 
through the medium of the animal they inhabit. They present no 
trace of a true circulation, and we merely perceive vestiges of nerves 
so extremely obscure, that many naturalists have doubted their ex- 
istence *. 
When those characters are found united in an animal with a form 
similar to that of this class, we place it here, although it may not in- 
habit the interior of another species. 
The injury caused by worms to animals, in which they become ex- 
cessively multiplied, is well known. The most efficacious agent for 
destroying those of the alimentary canal seems to be animal oil mixed 
with spirits of turpentine f. 
We will divide the Entozoa into two orders, which are perhaps 
sufficiently different in organization to form two classes, if we had 
the observations requisite to determine their limits. These orders 
are the 
Entozoa NematTouvEA, Rud., 
Which have an intestinal canal floating in a distinct abdominal 
cavity, a mouth and anus; and the 
Entozoa ParENcHyMATA f, 
Where the parenchyma of the body contains obscurely terminated 
viscera, most commonly resembling vascular ramifications, and some- 
times not visible. 
ORDER I. 
NEMATOIDEA, Rud.g 
This order comprises those whose external skin, more or less fur- 
nished with muscular fibres, and usually striated transversely, contains 
an abdominal cavity in which is a distinct intestinal cana], extending 
* For the anotomy of these Worms, besides the Entozoa of Rudolphi, see the Mem. 
of M. Otto, Soc. Nat. Berl., 1816, and the work of M. J. Cloquet. 
+ See Chabert, Traité des Maladies Vermineuses, and Rudolphi, I, p. 493. 
t~ They comprise the four last orders of Rudolphi. 
§ This order, with the exception of two the last genera, constitutes the ENromMo- 
ZAIRES APODES OXYCEPHALKES of M. de Blainville. 
