274 REPORT OF THE COMMISSIONER OP AGRICULTURE. 



long. Ova innumerable, smooth, elliptical, .085 mm to .09 ram (.0033-—.0035 



inch) long, and .05 mm (.002 inch) broad, each pole closed by a hood-like, 

 hemispherical valve, which becomes entirely detached at the time of 

 hatching. Embryos eel-like, developed in the body of the female, which 

 sots them at liberty only by its death and the destruction of its body; 

 at birth they measure .28 mai (.011 inch). 



Baljitat of the adults. — Trachea of pheasants. 



We shall now study in detail the various parts of the body in the fol- 

 lowing order: 



1. The general envelope of the body, consisting of the cuticle and t lie 

 muscular layer lining it ; 2, the digestive tube with its accessory parts; 

 3, the nervous system ; 4, the system of excretory vessels; 5, the male 

 and female genital apparatus as it exists in the most highly developed 

 adults. 



Body envelope. — The cuticle (Plate I, Fig. 5, a, a) is very thin, about 

 Q5jnm ^002 inch) thick, diaphanous, in appearance homogeneous, for we 

 have been unable to distinguish several layers, as has been done with 

 the larger nematodes. In young subjects it bears fine transverse striae, 

 but in old and united pairs of which the female is bearing eggs, and es- 

 pecially when these eggs contain well-developed embryos, the striae of the 

 trunk are completely effaced, but persist on the neck, where they can 

 be best seen in the female, in which they are .087 mm (.0031 inch) apart, 

 each fourth or fifth being deeper than the rest. Around the mouth the 

 cuticle expands like a collar or gamopetalous corolla, with four equal 

 rounded divisions forming four lips. At the same time it furnishes a 

 broad margin to the thick and scalloped border of the buccal armature. 

 In the male the cuticle goes to form the caudal, bell-shaped bursa, 

 which is cleft posteriorly and longer anteriorly, the latter aspect being 

 probably the true dorsal aspect of the worm. This bursa is supported 

 by six simple rays on each side. It caps the hemispherically projecting 

 vulva of the female and is united to it so intimately that even after the 

 death of the worms and their maceration in water it becomes torn be- 

 fore it can be separated from the vulva. 



The muscular layer which lines the internal surface of the cuticle 

 forms four longitudinal bands, as among the other nematoid worms, two 

 dorsal and two ventral, separated from each other by four linear inter- 

 vals. These muscular tracts are very delicate and permit the internal 

 organs to be seen through them. Only the superficial layer is distin- 

 guishable. It consists of longitudinal fusiform fibers (Plate I, Fig. 5, b) 

 and is lined with parenchymatous cells, which may be regarded as a 

 deeper muscular layer. 



Digestive apparatus. — In the digestive tract three regions may be dis- 

 tinguished — the mouth, the oesophagus, and the intestine. 



The mouth (Plate I, Fig. 4, Jl, B) opens on the anterior extremity of 

 the body. It is surrounded by four equal symmetrical lips already de- 

 scribed. At the four commissures of these lips may be seen four strong 

 bands or nervures, which unite the membraneous labial circle to the cori- 

 aceous armature of the mouth. This armature, made up of brown vhl- 

 tine, has the form of a complete hemispherical capsule or cupule, the 

 thick border of which is divided into symmetrical but unequal lobes. 

 These consist of two large lateral lobes, each corresponding to a lip, 

 two small anterior ones corresponding to the anterior lip and two small 

 posterior corresponding to the posterior lip. At the opposite and sym- 

 metrical notches at the extremities of the large lateral lobes are in- 

 serted the bands or ligaments which separate or whieh unite the mem- 

 branous lips. The bottom or background of the buccal cavity is a 



