Many phasmidian nemas have a rachis to which the 

 spermatogonia are attached {Atfcaris, Spironoura, Heter- 

 akis, the Strongylina in general and rhabditids). This 

 structure is apparently a process from the cap cell or 

 terminal epithelial cell of the testis similar to that of 

 the ovary (p. 139). 



Parts of the Male Reproductive System. The male 

 reproductive system consists of three or four major divi- 

 sions, the basic and more general divisions are testis, 

 seminal vesicle and vas deferens (Fig. 3). In some of 

 the more highly developed parasites such as Ascaris lum- 

 bricoidcs and Trichiiris siiis (syn. T. crenatus) a testicular 

 duct, the vas cffcreiis (Samenleiter) separates the testis 

 from the seminal vesicle. The terminal (posterior) end 

 of the vas deferens may be set off as an ejaculatory duct. 



Testis. In telogonic nemas the testis is subdivisable 

 into two regions, germinal zone and growth zone. In phas- 

 midians the cells of the growth zone first take the form 

 of a chord of six or more radiating series of cells attached 

 centrally to the protoplasmic rachis while in aphasmidians 

 they more often take the form of a four cell chord which 

 rapidly gives place to a double row and finally a single 

 chain of .cells. In all cases except hologonic forms the 

 testis is covered with an epithelium continuous vdth that 

 of the seminal vesicle (or vas deferens) just as the ovary 

 is covered with an epithelium continuous with that of 

 the oviduct. 



Vas efferens. In the few instances where such a struc- 

 ture has been described it is a duct separating the growth 

 zone of the testis from the seminal vesicle. It has a 

 rather high simple euboidal to columnar epithelium. 



Seminal vesicle. This is a dilated part of the male 

 gonoduct which acts as a storage organ for sperms. The 

 vas efferens may be considered as a specialized tubular 

 part of this structure. 



Vas deferens. The vas deferens is the chief part of 

 the male gonoduct. It is generally subdivided into tubular 

 and glandular regions and it may be covered by a 

 muscular layer either in its terminal region (near the 

 cloaca) or throughout its length. Thus only a part of 

 the structure is usually the functional ejector or ejacula- 

 tory duct. The detailed anatomy of the vas deferens 

 changes so much in the various groups that it vrill be 

 considered with the description of special anatomy. 



COMPARATIVE MORPHOLOGY 



As previously discussed the Phasmidia characteristic- 

 ally have a single testis. Among the aphasmidians the 

 Trichuroidea and Dioctophymatoidea also have a single 

 testis. No comprehensive surveys have been made which 

 would permit unequivocal characterizations of other 

 groups but two testes are the typical condition, so far 

 as known, of the remaining aphasmidian groups. 



Marked development of musculature covering the ejacu- 

 latory duct does not parallel parasitism as does marked 

 development of this layer in the female gonoduct. On 

 the contrary, it is very markedly correlated with the tax- 

 onomic group. So far as known, a heavily and extensively 

 muscled ejaculatory duct occurs only in the order Eno- 

 plida and holds true as a taxonomic character in all its 

 representatives studied by the writers. This is particu- 

 larly interesting since it so clearly confirms the place- 

 ment of the Trichuroidea and Dioctophymatoidea in this 

 order. 



Phasmidia. The male reproductive system of this group 

 has been studied by Schneider (1866) on Rhabditis 

 stron^yloides, by Leuckart (1876) on Ascaris lumhricoides, 

 by Cobb (1888) on Anisakis, by Looss (190.5) on Ancy- 

 lostoma, by Jagerskiold (1909) on Diehelyne, by Kriiger 

 (1913) on Rhabditis aspcra (R. aberrans) , by Magath 

 (1919) on Camallanus, by Steiner (1923) on Agamermis 

 dccaudata, by Musso (1930) on Ascaris, by Chitwood 

 (1930) on Rhabditis, by Tornquist (1931) on CamMllanus 

 and Cucullamis, by Chitwood (1931) on Oesophagostomum, 



Fig. 125. 



Male reproductive system- A — Rhabditis lambiliensis. B-C & F — 

 Hctrrakis (jalllvae. (B — Anterior part of gonoduct ; C — Posterior 

 part ot gonoduct ; F — Cross section at level of ejaculatory glands 

 and vas deferens). D-E — Chromadm-a qnndrilinea (D — Testis and 

 upper part of vas deferens: E — Spermatnzoan). G-H — Spironoura 

 affine. (G — Totomount male: H — Detail of valve indicated by vli) 

 in Gl. I-J — Sabatierin hilnrnla. fl — Anterior part of gonoduct; J — 

 Posterior part of gonoduct). K-L — Hcferodpra mnrioni (Monorclilc 

 form : K — Anterior part ot gonoduct : L — Posterior part of gono- 

 duct). M — Trilobus gracilis. G, After Mackin, 1936, 111. Blol. 

 Monogr., v. 14 (3). Remainder original. 



by Chitwood & Chitwood (1933) on Cephalobelhis, by 

 Yamaguti (1935) on Hcliconetna, by Baker (1936) on 

 Heterakis and by Mackin (1936) on Spironoura. Other 

 workers have made more or less casual observations in- 

 cidental to studies of spermatogenesis or postembryonic 

 development. 



The chief point of interest is the diversity in structure 

 of the vas deferens. At its junction with the seminal 

 vesicle there may be a well marked constriction. The 

 duct may be incompletely differentiated into an anterior 

 glandular region, comprising the greater part of its 

 length and a posterior non-glandular region or ejaculatory 

 duct, as in Rhabditis lanibdiensis, CephalobeUus papilliger 

 and Heliconema anguillae. (Figs. 124 C & G). In others 

 the anterior part may be subdivided into two sections 

 both of which may be glandular but the form of the 

 epithelium and the character of the secretory masses 

 difl'er in the two regions; this occurs in Rhigonema 

 infecta and Spironoura spp. (Fig. 124 D & E). In the 

 latter forms there is a distinct valve between anterior 

 and posterior sections. A similar division has also been 

 noted in Cueidlamis, Camallanus and Ascaris. At the 

 division point there is a muscular sphincter in many 

 forms. Musso and Magath claimed to have seen at least 

 one nucleus in the sphincter but other authors have been 

 unable to observe such. Muscular fibers in general are 

 always very sparse and confined to the second and third 

 (or just the third) zone of the ejaculatory duct. As 

 first pointed out by Voltzenlogel (1902) they appear to 

 originate with the posterior intestinal muscles and are 

 without nuclei of their ovra. 



A second general type in the Phasmidia is exemplified 

 by Rhabditis strongyloides (Fig. 124 A). In this form 

 the vas deferens has two large lateral pouches which 

 extend anteriorly on both sides. Here there has been a 

 differentiation of purely epithelial cells (forming the 

 anterior section of the vas deferens) and glandular cells 

 (forming the pouches and mid-section of the duct). These 

 pouches were first described by SiChneider and later studied 

 by Chitwood (1930) ; they are called ejaculatory glands 

 and are thought to form the adhesive cement deposited 

 on the female at copulation. They seem to have arisen 

 as a minor modification of the glandular region generally 

 typical of phasmidian forms. Looss has described very 

 similar though incompletely separated ejaculatory glands 

 in Ancylostoma and the writers have seen such in Oesoph- 

 a^ostomum. In the latter form the glandular cells are 

 often so placed as to give a laminated appearance (Fig. 

 124 B) and purely epithelial cells are distinctly recogniz- 

 able along the dorsal side of the vas deferens in the 

 glandular region. Chitwood (1931) described processes 

 from these cells which he considered possible homologues 

 of cilia; Cobb (1888) and Rauther (1918) had previously 

 described hair-like processes from the epithelial cells of 

 the vas deferens of ascaridids and trichuroids respectively. 

 None of these authors have observed vibratile movements. 

 In Heterakis Baker found ejaculatory glands very similar 

 in gross morphology to those of Rhabditis strongyloides 

 but in this form there are four distinct sections of the 

 vas deferens (Fig. 124 J). These sections consist of a 

 narrow tubular anterior part continuous with the seminal 

 vesicle, two wider glandular sections, separated from one 

 another by a valve, and a short posterior ejaculatory 

 part. In this case the paired ejaculatory glands open 

 into the anterior end of the first glandular section. Wheth- 

 er they should be interpreted as outpoeketings of that 

 part or as differentiated lateral outpoeketings of the 

 tubular anterior section, is not known. 



Aphasmidia. Study has been made of the male repro- 

 ductive system of members of this group by Eberth (1860) 

 on Trichnris, by Leuckart (1876) on Trichuris, by de 

 Man (1886) on Enoplus, Anticoma, Tripyloides and Eu- 

 chromadora, by Cobb (1890) on Anticoma, by Jagerskiold 

 (1901) on Cylicolaimus. by Tiirk (1903) on Thoracosto- 

 ma. by Schepotieff (1908) on Desm^jscolex, Greeffiella 

 and Epsilnnewa, by Rauther (1918) on Trichuris, by 

 Steiner (1923) on Agamermis, by Cobb (1928) on Spirina 

 and by Cobb (1929) on Draconema. In addition to these 

 papers numerous authors have noted the number of 

 testes in descriptions of species. Cobb, however, is the 

 only author who consistently provided such information. 



As previously noted above, the two aphasmidian 

 orders, so far as existing information goes, may be separ- 

 ated upon the basis of muscular development of the 

 ejaculatory duct. 



163 



