OCR Text |
Show 1894.] NEMATODE PARASITES. 535 commences (figs. 4 and 5), two being situated on the ventral surface aud one, by far the largest, on the dorsal. In the centre of each is an oval body, which stains more deeply than the substance in which it lies, though that also stains well, and which to this extent, at any rate, resembles a nucleus. On the other hand, its structure is not that of a very typical nucleus ; it consists of a thick coat which encloses a number of deeply staining large granules, which have the appearance of concretions. The substance of the matrix in which these oval bodies lie is also differentiated ; it consists of a number of apparently homogeneous bodies pressed together, with thin lines or triangular chinks between them, which stain somewhat more deeply than the rest. In spite of the peculiarities of the structure of these " Gewebepolstern," I a m inclined to regard them as cells, but I can offer no suggestion as to their function. I could not trace in m y sections any connection between them and the lateral lines or with the nerves ; they seem to fade away at their ends into the connective tissue which in this region surrounds the rectum. DESCRIPTION OF PLATE XXXV. Sections of Ascaris transfuga. Fig. 1. Transverse section of the middle of the body. The body-cavity is almost occluded by the medulary part of the muscle-cells. 2. Longitudinal section through the line of junction of the oesophagus with the intestine. The coagulated fluid of the body-cavity is seen broken up into strands and strings. 3. A transverse section of part of the wall of the intestine. 4. A longitudinal section through the line of junction of the intestine with the rectum and the anus, to show the position of the problematical bodies and of the sphincter muscle. 5. A transverse section through the rectum showing the relations of the problematical bodies. 6. Section of the integument in the anterior region, to show the lateral line and the fin strengthened by the forked plate. Explanation of letter a. Cuticle. b. Subcuticular layer. c. Contractile portion of muscle-cells. d. Body of muscle-cell containing the nucleus. e. Lateral canal. /. Dorsal nerve-cord. q. Yentral nerve-cord. h. Dorso-lateral nerve-cord in lateral line. i. Bursal nerves. ;'. Problematical organs surrounding rectum. •ing in all the figures. k. Sphincter muscle surrounding rectum. I. Anus. m. Coagulated fluid of body-cavity. n. Muscular oesophagus. o. Intestine. p. Layer full of vesicles at inner end of cells lining intestine. q. Cuticle covering intestine. r. Forked plate which strengthens the lateral flaps on anterior end of body. 35* |