tion. At the junction of the seminal vesicles, the vas 

 deferens is given off as a single tubular canal directed 

 posteriad. This structure is highly glandular throughout 

 its length. Rarely (Sabritierid) the posterior part may 

 be set off by a constriction (Fig. 124 U). A very short 

 non^glandular terminal division acts as ejaculatory duct. 

 In monorchic forms (Clirnntodora) the arrangement (Fig. 

 124 S) is so similar to that of Rhabditis Urmbdiensis that 

 it needs no special description. De Man mentioned special 

 copulatory glands in Euchromadora and Schepotieff did 

 the same for Desmoscolcx but in neither instance is an 

 adequate description or illustration furnished. 



Three types of spermatozoa are known in the Chroma- 

 dorida, these being standard ameboid (typical of the 

 Phasmidia), flagellate, and hollow. Of these, the flagel- 

 late type of spermatozoan is known only in Halanonchus 

 and the ameboid is known in plectids, chromadorids and 

 Dcsnwiaimufi. The hollow sperm is a very interesting and 

 pe'juliar structure. As a rule it is large with a narrow 

 ectoplasm radially striated by fibrils and a central vacu- 

 ole. The nucleus usually lies next to the periphery and 

 is quite small (exception Spirina parasitifera). This 

 type of sperm is known to oc:ur in axonolaimids, come- 



somatids, cyatholaimids, Tripyloides, Microlaimiis, Mono- 

 posthia and Metachroniadora. 



Within the Order Enoplida the musculature of the 

 ejaculatory duct is usually very prominent and may 

 extend to the seminal vesicle. So far as known, all 

 Enoplida are diorchic except the hologonic groups Trich- 

 uroidea and Dioctophymatoidea. In these the musculature 

 of the ejaculatory duct is particularly thick, giving a 

 laminated appearance due to the presence of several layers 

 of muscle cells. Steiner (1923) has shown the entire vas 

 deferens of Agamermis decaiidata as being covered by a 

 well developed muscular layer. The writers have found 

 the ejaculatory duct covered by a particularly well de- 

 veloped layer of oblique muscles in Metoncholaimus (Fig. 

 126 S) Trilobii.H (Fig. 126 DD-EE), Enoplus (Pig. 126 

 L-N), and Phanodermopsis; the muscle cells in these 

 forms extend only half way around the ejaculatory duct, 

 extending obliquely anteriad from the medio-ventral to 

 the medio-dorsal line. In Metoncholaimus the musculature 

 extends anteriad, in a less well developed manner for 

 over half the length of the vas deferens while in Enoplus 

 the musculature extends throughout the length. Glandu- 

 lar activity is evident throughout the vas deferens and 

 the anterior part of the ejaculatory duct in Enoplus 

 while it is confined to the vas deferens in Ti-ilobus, Thora- 

 costovia and Cylicolaimus and is confined to the non- 

 muscular part of the vas deferens in Metoncholaimus. 

 The paired testes are continuous with paired seminal 

 vesicles except in Enoplus where the junction of posterior 

 testis and seminal vesicle appears to have been shifted 

 anteriad. So far as known, the spermatozoa are ameboid 

 in the parasitic groups (Merniithoidea, Trichuroidea and 

 Dioctophymatoidea) while in the free-living forms they 

 are definitely flagellate as in Trilobus, spindle to tear 

 drop shaped as in Mononchus, Tripyla, Phanodermopsis, 

 Enoplus and Actiiiolaimus or rounded as in Metoncholai- 

 mus and Thoracostoma. 



*Cobb (1928) described the "Gametogenesis" of Spirina para- 

 sitifera by including in the sperm development the formation of a 

 128 cell "spermatophore" due to amitotic division of the spermatid. 

 Re-examination of this species shows that what he interpreted as 

 the spermatid is the enormous hollow spermatozoon and what 

 he interpreted as the nuclei of the spermatophore are secretion 

 globules in the wall of the vas deferens. The latter are arranged 

 in transverse rows in the narrow transversely elongate epithelial 

 cells. 



Bibliography 



Anaplecilts granulosus. 

 system. Original. 



Fig. 127. 



Reconstruction of male reproductive 



AcKERT, J. E. 1931. — The morphology and life history 

 of the fowl nematode, Ascaridia lineata (Schneider). 

 Parasit, v. 23 (3): 360-379, figs. 1-25, pis. 13-14. 



Alicata, J. E. 1935. (1936). — Early developmental stages 

 of nematodes occurring in swine. Tech. Bull No. 

 489, U. S. Dept. Agric. 96 pp., 30 figs. 



Artigas, p. 1930. — Nematoides dos generos Rhigonema 

 Cobb, 1898 e Dudekemia n. gn., (Nematoda: Rhigo- 

 nemidae n. n.). Mem. Inst. Oswaldo Cruz, v. 24 (1): 

 19-30, pis. 8-14, figs. 1-32. 



Atkinson, G. F. 1896. — Root galls of cotton (Heterodera 

 radicicola (Greeff) Muell). (In his Diseases of 

 cotton) Bull. (33), Office Exper. Stations, U. S. Dept. 

 Agric, pp. 311-316,, fig. 8. 



AuGSTEiN, O. 1894. — Strongylus filaria R. Arch. Naturg., 

 60 J., V. 1 (3) : 255-304, pis. 13-14. 



Baker, A. D. 1936.- — Studies of Heteiakis gallinae 



(Cimelin, 1790) Freeborn, 1923, a nematode parasite 



of domestic fowls. Tr. Roy. Canad. Inst., v. 21 (1) : 51- 

 86, pis. 1-15. 



Balss, H. H. 1906. — Mitteilungen iiber einen abnormen 

 weiblichen Geschlechtsapparat von Ascaris liimbri- 

 coides L. Zool. Anz., v. 30: 485-487, 1 fig. 



Bastian, H. C. 1865. — Monograph on the Anguillulidae, 

 or free nematoids, marine, land, and fresh-water; 

 with descriptions of 100 new species. Tr. Linn. Soc. 

 Lond. V. 25 (2) : 73-184, pis. 9-13, figs. 1-248. 



1866. — On the anatomy and physiology of the 

 nematoids, parasitic and free; with observations on 

 their zoological position, and affinities to the echino- 

 derms. Phil. Tr. Rov. Soc. Lond. v. 156: 545-638, 

 pis. 22-28. 



156 



