106 ASYMMETRY OF THE NEMATODE 



pendages or tubercles, which through the middle of the body are about half as 

 high as they are wide. The tubercles are of rounded or ellipsoidal form, and 

 when seen en face sometimes show on their punctate surface the presence of three, 

 four, five, or more exceedingly minute papilla-like elements encircling the axis of 

 the appendage, this axis of course being radial and perpendicular to the surface 

 of the body. In the specimen from which the description was derived, which 

 appeared to be an average female about to undergo the final moult, there were 

 sixteen of these appendages, forming a dextral row extending from the lips to 

 near the anus. Those near the ends of the series were smaller than those near 

 the middle, that on the lips being the smallest of all. Throughout the middle 

 portion of the body the tubercles are of rather uniform size. Anteriorly they be- 

 gin to diminish in size near the base of the neck, so that the bluntly conoid tu- 

 bercle opposite the base of the pharynx has a diameter only one-third as great as 

 that of the one near the middle of the body. The posterior tubercle, near the 

 anus, is of about the same size as that opposite the base of the pharynx. When 

 seen in profile, that is, when the nematode is viewed dorso-ventrally, the tubercles 

 exhibit somewhat the same degree of striation as the adjacent cuticle, but the 

 striae, or elements thereof, appear as if arranged in a somewhat fan-shaped man- 

 ner. When the body is arcuate and twisted, so that the row of appendages is on 

 the outside of the curve, the distance between the appendages at the middle of 

 the body nearly equals the diameter of one of the appendages. When the body 

 is curved in the other direction, the tubercles may be nearly in contact. The ex- 

 terior of the tubercular appendages is distinctly striated, and sometimes tessel- 

 lated, the striae being of about the same size and nature as those of the rest of 

 the cuticle. 



The following is a detailed description of these interesting tubercles as they 

 occurred on an adult male specimen fixed in Fleming's solution, and examined 

 soon afterward in water. The specimen was arcuate and the tubercles were on 

 the inside of the curve. The first or labial tubercle, standing halfway between 

 the two relatively large and apparently dextral submedian cephalic setae, ap- 

 peared somewhat thumb-shaped in contour, and when seen in optical section 

 seemed to have a refractive chitinous core of a slightly greenish color. This tu- 

 bercle was arcuate, and its apex was turned outward so as to be nearly at right 

 angles to the body axis. The second tubercle, slightly behind the base of the 

 pharynx, was bluntly conoid, the longitudinal optical section being approxi- 

 mately equilateral. The cap or outer half of the cone was a grayish green refrac- 

 tive chitinous element, whose structure showed comparatively little detail. The 

 contour of this cap when seen in optical longitudinal section indicated the pres- 

 ence of a slight constriction half way between its apex and its base. Inside the 

 cap the tubercle appeared as if radially striated, the number of striae being about 

 ten. As these striae appeared to be more or less visible in every longitudinal op- 

 tical section,it would seem as if they must be the optical expression of a columnar 

 or laminated structure. When the tubercles were viewed in longitudinal optical 

 section, the intermediate somatic cuticle, that is the cuticle between successive 

 tubercles, presented refractive features related to the tessellation so strikingly 

 displayed when the animal is viewed from the right side. The plainer or less 

 complicated portions of the cuticle, as thus seen in longitudinal section, repre- 

 sent the "lacunae" of the tessellation, while the refractive places represent the 



