II. A FLORA WITHIN ANIMALS. 39 



13. ON SOME PARASITIC PHYTOID BODIES, THE NATURE OF WHICH is OBSCURE. 



Among the objects which I detected with a good deal of constancy within the 

 ventriculus of Passalus cornutus, is one which has puzzled me exceedingly. It is 

 an elongated tubular cellule, attenuated at both ends, which I formerly described, 

 probably -too hastily, as an entophyte, under the name of Cryptodesma? Up to the 

 present time, I have not been able to satisfy myself of its true character ; whether 

 it be really an entophyte, or only the epithelial cells of the ventriculus, elongated 

 by endosmosis (PL X. 3). One would suppose it to be an easy matter to resolve 

 this question, but there are many difficulties in the way of its determination. Its 

 constancy of existence is no objection to its entophytic character, for certain 

 undoubted entophytes, as Enterobryus altenuatus, Arthromitus, and Cladopliytum, 

 and an entozoon, Hystrignathus rigidus, are quite as constant in their existence. 



The epithelial cells of the mucous membrane are ordinarily in the form of 

 columnar prisms. The bases of attachment of these I have often very distinctly 

 observed through the translucent basement-membrane from the exterior ; but 

 their sides, even at the edge of a section of the mucous membrane, I could never 

 satisfactorily examine, on account of their being totally obscured by the vast 

 profusion of Arthromitus, Cladophytum, and Corynocladus ; more particularly, 

 however, by a peculiar vegeto-granular substance, growing everywhere from the 

 surface of the membrane. In the larva of Passalus, these cells can readily be 

 distinguished,, and in this they are observed to be prismoid, and are not altered 

 by the endosmosis of water, so as to assume the form of the phytoid cells in 

 question. These latter were always seen detached, usually in groups, or adhering 

 to masses of granular matter, but were never observed attached to the hair-like 

 appendages of the mucous membrane. 



In structure, they resemble more the cellules of a fungous mycelium, than the 

 algoid plants previously described, consisting of a delicate tubular cell, usually 

 somewhat irregular, and inclosing very finely granular contents. Acetic acid does 

 not dissolve them, nor does it destroy the appearance of epithelia observed through 

 the basement-membrane. 



I have examined numerous individuals of Passalus, to ascertain the true nature 

 of the bodies described, and sometimes almost concluded they were entophytic 

 parasites ; at others, that they were really elongated epithelial cells ; and, for the 

 present, I leave the subject, with the intention of investigating it more closely and 

 patiently at a future time. 



In addition to the entophyta described in the preceding pages, which inhabit 

 the alimentary canal of Julus marginatus and Passalus cornutus, there is also found 

 within the ventriculus of these animals a peculiar phytoid substance, which is 

 worthy of attention. 



The surface of the mucous membrane of the ventriculus of Julus marginatus, is 



1 Proc. Acad. Nat. Sci., Phila., iv., 250. 



