1894.] 



NEMATODE PARASITES. 



535 



commences (figs. 4 and 5), two being situated on the ventral 

 surface and 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, xesembles 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 con- 

 cretions. The substance of the matrix in which these oval 

 bodies lie is also differentiated ; it consists of a number of ap- 

 parently 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 am inclined to regard them as cells, 

 but I can offer no suggestion as to their function. I could not 

 trace in my 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 Aacaris 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 cesophagus 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 junclion 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 fia strengthened by the forked plate. 



Explanation of lettering in all the figures. 



a. Cuticle. 



b. Subcuticular layer. 



c. Contractile portion of muscle-cells. 

 Body of muscle-cell containing the 



nucleus. 

 Lateral canal. 

 Dorsal nerve-cord. 

 Ventral nerve-cord. 

 Dorso-lateral nerve-cord in lateral 



Une. 

 Bursal nerves. 

 Problematical organs surrounding 



rectum. 



d. 



e. 



/. 



H- 

 h. 



Sphincter muscle surrounding 



rectum. 

 Anus. 



Coagulated fluid of body-cavity. 

 Muscular oesophagus. 

 Intestine. 

 Layer full of vesicles at inner end 



of cells lining intestine. 

 Cuticle covering intestine. 

 Forked plate which strengthens the 



lateral flaps on anterior end of 



body. 



35* 



