442 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 22, NO. 12 



much elongated unicellular salivary gland, e.g. 43, and dot gl sal, located 

 along the corresponding sector of the oesophagus and reaching back even to 

 near the base of the neck, where the corresponding three nuclei, 41, may be 

 seen, about one body-width in front of the prominent constriction, 13, sepa- 

 rating the oesophagus from the intestine. Each gland empties through a 

 perforation, 27, in the corresponding onchium, by means of an inconspicuous 

 ampulla and a very fine duct, about one micron across. The distribution of 

 the salivary glands among the radial contractile fibers of the oesophagus may 

 be indicated by the granules, one micron or less in diameter, to be seen in 

 various parts of the glands, e.g. at dct gl sal. In favorable specimens the ducts 

 of these glands, when filled with this granular secretion, can be followed 

 throughout the length of the oesophagus, and the glands are then seen to have 

 numerous short lateral branches, (see from 43 forward). The much larger, 

 though inconspicuous pigment granules of the oesophagus are scattered through- 

 out the organ. 



The external amphids, 32, 51, one on each side of the head, are somewhat 

 escutcheon shaped, being symmetrical only to a longitudinal line, and are 

 longer transversely than longitudinally. The anterior border of each amphid 

 is removed from the anterior extremity of the nema a distance about equal to 

 the radius of the head. They are much more obvious if looked at dorso-ven- 

 trally, when they are distinctly seen to be two pocket-like entrances to internal 

 sensory organs, the internal amphids, located laterad in the back part of the 

 head. Each of the external amphids is about one-fourth as wide as the corre- 

 sponding portion of the head and about two-thirds as long as it is wide. Each 

 outer amphid connects with a sensilla, 54, or receptor, close behind, by means 

 of an exceedingly narrow and very short (two and a half microns) but strongly 

 refractive, duct, shown in the figure. The sensilla is one-fifth as wide as the 

 head and lies opposite the basal part of the pharynx and is connected back- 

 ward with the central nervous system by a lateral nerve, 55, just beneath the 

 body wall. The details of the sensilla, 54, are usually difficult to see except 

 when specially stained. The amphids are held to be chemical sense organs. 



The oesophagus, 12, 36, is cylindroid, enlarging very slightly posteriorly; 

 behind the pharynx it is three-fifths, at the nerve-ring one-half, and finally 

 two-thirds as wide as the corresponding portion of the neck. The refractive 

 membranous "triquetrous" lining of the eosophagus, mainly about one micron 

 thick, but two microns in the axial parts, is a distinct feature throughout the 

 organ, and finds main optical expression in what appear as two or three closely 

 approximated refractive, often slightly sinuous, axial elements, and, in the 

 ordinary closed condition of the oesophagus, seeming to occupy about one- 

 eighth of its width. The radial musculature of the eosophagus, to be seen 

 throughout its length, consists of fine strands and is accompanied by only a 

 slight amount of yellowish granular matter. There are no cuticularized 

 valves in the oesophagus. 



The intestine. The intestine, 83, 94, which becomes at once two-thirds as 

 wide as the body, is thick-walled and is composed, as is usual in nemas, of a 

 single layer of cells, 69 and vicinity, here of such a size that about twelve are 

 required to complete the circumference. The walls of the cells are only 

 faintly visible except sometimes in the outer colorless part, 1, 76. Usually the 

 lumen of the intestine, (see just behind cardia, 14) can be seen only faintly, 

 since the lining of the intestine is not refractive. As the nema bends back 

 and forth, the food content of the intestine, e.g. at 92, may be seen to move 

 backward and forward in the lumen. This nema appears to swallow mud 



