Sphaerolaiminae to exhibit ovai'ial I'eduction is well rec- 

 ognized but no one would today exclude amphidelphic 

 genera from these groups providing other charactei-s 

 conformed. In all nemic groups one notes the appearance 

 of monodelphy and among free-living nemas, as also 

 among parasites, this usually means posterior shifting of 

 the vulva because it is the anterior ovary that persists. 

 Exceptions to this rule are HalanoticIiKs macrainpliidium 

 (Monhysteridae) . O.vystomina cylindraticauda (Eno- 

 piidae), Dori/Iaiiiius moiihi/stera (Dorylaimidae) in all of 

 which the vulva is shifted anteriad, the posterior ovary 

 having persisted. In parasites, exceptions (Trichuroidea, 

 UiDCfophtima, Soboliphi/me) to the rule seem to be as 

 numerous as conformists but here there is probably some 

 functional or fundamental reason as yet not understood. 



If there is any single characteristic which might serve 

 to contrast free-living aphasmidians with fi-ee - living 

 phasmidians in the female reproductive system, it is a 

 tendency toward the formation of larger, fewer eggs, 

 often accompanied by marked relative shortening of the 

 growth zone. The very large size of one or two maturing 

 oogonia may give cause for a noticeable attenuation of 

 the ovary, (Fig. 119 F). There are ex-ceptional aphas- 

 midians which produce numerous relatively small eggs 

 (Metonchohiimiis pristiurus, Actinolaiimis sp. Fig. 120 

 G-H) and in such forms the ovaries are much more 

 elongated, due to a more extensive growth zone. 



The semi-diagrammatic illustrations speak largely for 

 themselves. We need only call attention to the appai'ent 

 absence of an oviduct in Chromadora (Fig. 120 E) and 

 'i'heristus (Fig. 117 R), the individual and distinct ovi- 

 duct of Anaplectus, Axonolaiiiins, Stthatieria, etc. and 

 the modified oviducts of Mononchus, Trilobus, and 

 Actinohnmus. In the latter forms there is marked flatten- 

 ing of the oviduct against the ovary (Fig. 120 H) and 

 eventually the oviduct disappears as an entity, the ovarial 

 epithelium being separated from the germ cells on one 

 side so that the mature ovum may slip between the 

 germ cells and the epithelium. This feature was first 

 called attention to by Jiigerskiold (1901). The varied 

 modifications serving the function of seminal receptacle 

 or spermatheca are interesting from the standpoint that 

 they may usually be regarded as the ovarial end of the 

 uterus. Uterine outpocketing or separation from the 

 oviduct in axonolaims and comesomes (Figs. 116 L-N) 

 is sufficiently spectacular to lend considerable weight to 

 hypothesized comesomatid-axonolaimid relationships. 



Vaginal cuticle and muscular developments in free- 

 living aphasmidians are often quite characteristic of 

 species and genera but are, unfortunately, not easy to 

 describe. Laminated vaginal musculature occurs very 

 rarely, and in the genus Trilobus (Fig. 120 J) it is used 

 as a specific chai^acter, being absent in many species. 

 Often the vaginal cuticle appears in optical section of 

 totomounts as two paired sclerotized rods (Fig. 119 I). 

 Mononchs and dorylaims are particularly notable in this 

 respect. 



There is a very peculiar system of organs connected 

 with the female reproductive system of oncholaimids 

 first described by de Man (1886) and later studied by 

 zur Strassen (1894) and Cobb (1930) and named the 

 demanian system by Cobb. In description we can not do 

 better than quote Cobb. 



"Demanian Vessels: In adult female nemas (Oncho- 

 laims) a complicated double system of efferent tubes; 

 connecting (1), with the middle or posterior part of the 

 intestine through an osmosium, and (2), with the uterus 

 (or uteri) ; these two efferents being confluent at a special 

 glandular 'gateway', the uvefte, and emptying thence 

 backward and outward, through one or two ducts having 

 more or less moniliform affluent glands. Normally, the 

 ducts lead to exit pores in the body wall, usually lateral, 

 one or more on each side, near the iDase of the tail." 

 Cobb decided, on the basis of a systematic exploration 

 of the theoretic possibilities, that the course of flow in 

 the demanian system is from the intestine and uterus, 

 through the moniliform glands to the exterior. Cobb 

 associated this system with the formation of a "gelatin 



Fig. 119. FEMALE REPRODUCTIVE SYSTEM. 



A-C — Spirononra affine (A, showing posterior uterine branch. B. 

 anterior branch; C, entire female). D — Khigonema infectum. E, 

 Aphelenchoides fragariae (Chrysanthemum strain). F — Crypton- 

 chits nudtis. G, HnJarionchiis macramphUlnm. H — Ditylenchtis dipsaci. 

 I, Oxystotnina cylindraticauda. 



A-C. after Maoliin, 1936. 111. Biol. Monographs v. 14 (3). Re- 

 mainder original. 



like" mass in the uterine lumen of gravid females which 

 he believed flows out through the posterior pores and is 

 deposited as a "sticky, non-water-soluble, nearly color- 

 less secretion possibly utilized during agglomeration and 

 copulation and also presumably to preserve the batches 

 of eggs after deposition and segmentation." The writers 

 (1938) observed orange pigmentation in the demanian 

 exit ducts of Oncholaimus oxyuris which was similar 

 to that found in the olivaceous sphaeroids of the same 

 s;iecies. 



Parasitic nemas. Seurat recognized the fact that the 

 female reproductive system increases in complexity with 

 the degree of parasitism. He noted tendencies in this 

 direction among rhabditoids (ex. Rhubdias) and tylen- 

 choids (ex. Sphaerularia) . There is everywhere a tend- 

 ency toward increased egg production, increased length 

 and coiling of ovary, oviduct and uteri, and formation 

 of complicated muscular ovejectors, but each parasitic 

 group seems to have followed its own course of de- 

 velopment. 



Strongyliyia. Members of the Strongylina have a basic- 

 ally equatorial or slightly post-equatorial vulva joined 

 to amphidelphic flexed gonoducts by means of a short 

 transverse vagina and paired opposed ovejectors. Such 

 a condition is approximately realized in Dictyncaultis fil- 

 aria (Fig. 116 Q) and Hctcmovchtis contortus (Fig. 116 

 T). Critical studies of the female organs of strongylins 

 is due to the investigations of Augstein (1894), Looss 

 (190.5), Maupas and Seurat (1912), and Seurat (1920). 

 In addition Ran.som (1911). Seurat (191.5), Veglia (1916), 

 Thapar (1925), and Alicata (1935) have made con- 

 tributions. 



Varied nomenclatures applied to the ovejectors of 

 strongylins have already been mentioned. The vagina 

 vera in this group is always a short, more or less trans- 

 verse flattened tube. As noted by Looss, the ectodermal 

 cuticle stops suddenly at the junction of vagina and 

 oveiector (Fig. 118 I). Seurat (1920) was apparently 

 under the impression that the entire ovejector was of 

 p"todermal origin because it was lined with "cuticle". 

 However, the character of this cuticle is quite different 

 from that of the vagina vera and external body covering. 

 According to the observations of Alicata (1935) the 

 ovejectors are formed from the central part of the genital 

 primordium in Hyostrotigylus ruhidus while the vagina 

 is an ectodermal invagination. With Looss (1905) we 

 regard the ovejectors of strongylins as of totally uterine 

 origin. There seems to be no evidence of glandular ac- 

 tivity in any part of the ove'ector so the term glazing 

 (or varnishing) gland (see p. 147) is a misnomer. Each 

 ovejector is composed of two (Fig. 118 I) or three parts 

 (Fig. 118 OC). Its function in Ancylostoma duodenale 

 was described by Looss as follows: 



"The function of the pars haustrix (infundibulum) is 

 evident from its structure. The contraction of the spiral 

 muscles causes it to shorten, its inner cavity at the 

 same time widening. The decrease of pressure thus 

 brought about cannot be compensated for from behind, 

 this being prevented by the funnel-shaped ends of the 

 most anterior cells (I). The diminution of pressure 

 therefore tells on what lies in front, sucking in the egg 

 located nearest the pars haustrix. This egg is prevented 

 from being pushed back into the uterus by a contraction 

 of the anterior circular musculature of the pars haustrix, 

 which, during the enlargement, has been passively ex- 

 tended. So soon as the egg has passed the funnel made 

 by cells I, its way out is unimpeded. The return of the 

 .spiral musculature of the pars haustrix to its normal 

 condition drives it into the pars ejectrix and it is ejected 

 hy the successive contractions of the muscles of the 

 knobs. In passing from one knob to another, the egg 

 follows a zig-zag cour.se, but cannot escape backward, 

 being prevented from doing so by the prolongations of 

 the epithelial cells directed backward. In this way the 

 egg is forcibly propelled onward into the vagina; from 

 this it may be ejected either by pressure of the eggs 

 forced on behind it or through the action of the vulvar 

 muscles." 



In Anci/lostoma and several other members of the 

 Strongylina each ovejector consists of only two parts. 

 The uterine end, which Looss termed the pars haustrix 

 (Fig. 118 I) consists of two sets of four cells (I and II). 

 This part apparently corresponds to the two parts of 

 the ovejector of Nematodirus mmiritaniens (Fig. 118 BB) 

 described by Maupas and Seurat (1912) as trunk and 



145 



