256 Dr. Von Siebold on a Douhle-lodied Intestinal Worm, 



a cavity in which the intestines lie inclosed. The intestines 

 are here bathed by a red liquid, in which only a few vesicles 

 and particles swim. This is the liquid which imparts to the 

 worm the beautiful red colour. Whether the cavity of the 

 male branch stands in connexion with the cavity of the other 

 parts of the body, which are continued into the female branch, 

 whether it is separated from it by a partition, I could not de- 

 termine, on account of the small number of specimens which 

 I had to examine. On injuring the skin the red liquid flowed 

 out without the intestines being pressed forwards ; from which 

 I conclude, that the skin which covers the intestines does not 

 possess that elasticity which is common to the skin of the 

 cylindrical worms. The skin was almost even, and not as in 

 most of the Neinatoidea, annulate. 



The circular mouth-aperture leads to a cavity of the form of 

 a basin, which does not consist, as in the Distomum, of a mus- 

 cular tissue, but of a firm horny substance of a dark colour, 

 which is visible through the skin : its outer border has six in- 

 dentations, and is so inclosed by the tegumentary covering 

 that it is everywhere kept at the same distance from it. 



Opposite the mouth the basin is pierced by a small aperture, 

 through which we arrive at the oesophagus. I saw this aper- 

 ture surrounded by six minute knots or hooks. As I now 

 turn to the description of the digestive organs, I shall only 

 speak of the male branch. The oesophagus of the male branch 

 is very much prolonged, begins small at the inferior small 

 aperture, increases in the middle, and ends rather rounded. 

 Its colour is dirty yellow ; its structure, like that of many Ne- 

 matoidea, is very muscular, and is traversed by a trihedral 

 canal. Behind it commences the somewhat broader, more 

 simple, and red-brown-coloured intestine, which passes in a 

 tortuous manner to the branch, and terminates in a cul-de-sac 

 before the connection of the latter with the body. The oeso- 

 phagus of the female branch is just the same as the former as 

 to colour, situation, and structure, and is only shorter and more 

 compressed, from which it appears in the shape of a pear 

 turned upside down. The same red-brown simple intestine 

 which arises from it, is somewhat broad, extends in a more 

 tortuous manner through the whole body, and finishes in a 

 cul-de-sac before the caudal extremity. Both intestinal canals 

 contain very small granules, which may be well compared with 

 pigmentary molecules. On opening the intestinal canal only a 

 few of these molecules force themselves out, the rest remain 

 attached to the inner surface of the intestine. If a piece of the 

 intestine is examined under a microscope, it has just the ap- 

 pearance as if it possessed vascular reticulations, which is 

 caused by the molecules being separated into several heaps 



