Fig. 123. FEMALE REPRODUCTIVE SYSTEM. 

 Halifhomiolaimns robusius. Original. 



the uteri. The various arrangements have been studied 

 by Seurat (1920) in Acitarlc, laticeps, Tetrameres fissi- 

 sphia, Spinira gastrophila. Pfotospiriira nnmidica and 

 Abbreviata abbreviata (Fig. 118). The Physalopteridae 

 present more taxonomic difficulty than any other gvoup 

 because of their tendency toward polydelphy. Ortlepp 

 (1922, 1937) divided the genus Physaloptera into four 

 groups (Didelphys, Tridelphys, Tetradelphys and Poly- 

 delphys) on the basis of uterine and ovarial numbers. At 

 tlie same time he attempted to follow out correlations 

 according- to the method of uterine origin, i. e., whether 

 the uteri arose direct from the base of the egg chamber 

 (trunk) (Pig. 118 X) or were connected to the egg 

 chamber by a common trunk (Fig. 118 Y). In the di- 

 delphic, tetradelphic and polydelphic types the two pos- 

 sibilities both made their appearance. Schulz (1927) 

 compared these data with cephalic characters and came 

 to the conclusion that ovarial number must be considered 

 a secondary character, and mode of origin of the uteri a 

 tertiary character. Thus the old genus Physaloptera was 

 divided into three genera on the basis of cephalic 

 structures, each genus being subdivided on ovarial 

 number. Apparently Sandground (1936) has substan- 

 tiated Schulz in discarding mode of origin of the uteri 

 as a character since he showed three modes of iiterine 

 origin in the species Abbreviata poicilomefra (Fig. 118 

 LL-MM & 00). 



Polydelphy outside the Physalopteridae is unusual, 

 having been recorded only in Ehieophora poeli and Tanqua 

 tiara (Fig. 116 U), Dipetalonematidae and Gnathostoma- 

 tidae respectively. In the latter form one encounters poly- 

 delphy and amphidelphy associated, there being three 

 anterior uteri and one posterior uterus all of which empty 

 into a common egg cham'ber which is in turn connected 

 with the vagina (Monnig, 1923). 



Mermithoidea. The Mermithoidea are purposely taken 

 up here, along with the vertebrate parasites because they 

 exhibit the same characteristics of vaginal development 

 as do the more generally considered forms. Steiner 

 (1923, 1926, 1929) has described a remarkable series of 

 stages in the formation of an elongate muscular vagina 

 from the transverse slit characteristi? of all dorylaims, 

 as seen in Mesomcrmis bursata (Fig. 118 FF), enlarge- 

 ment as in Bathymennis sphaerocephala and elongation 

 as in Hydromerinis leptoposiliia (Fig. 118 Z), to the 

 comnlex type found in lAmvomermis eiivaqinata. As in 

 many other parasitic groups, Steiner (1923) found that 

 there is elongation of the oviduct. Mermithoids are al- 

 wavs amphidelphic. so far as known. 



Trichuroidea - Dioctophymatoidea (Hologonia). The 

 specific details of differentiation of these two groups 

 from other vertebrate parasitic groups rests not only on 

 reproductive system, but on hypodermis, coelomocytes and 

 stylet formation. Ju.=t how significant is the altered type 

 of germ cell origin, upon which Rauther (1930) based 

 the Hologonia, we are not prepared to say. All members 

 of the group are monodelphic and in all with the ex- 

 ception of the genera Exatronoylides and Hystrichis the 

 vulva is anterioi'ly shifted. The muscular ovejector so 

 far as kno"'n is of ectodermal origin. 



Male Reproductive System 



GENERAL MORPHOLOGY 



There has been no comparative morphological study on 

 the male renroductive system compara'ale to that of Seurat 

 on this system in the female. This is due, at least par- 

 tially, to the structural uniformity of the male apparatus 

 which lacks distinct adaptation coincident with para- 

 sitism; as in the female, with parasitism 

 the male reproductive system increases in length 

 but accessory structural diffei-entiations are not apparent. 



There may be either one or two testes. If two, they 

 are arranged in onposite directions except in Heterodera 

 marioni and Anticoma typica. In the first species there 

 may be either one or two testes continuous posteriad with 

 a single seminal vesicle; transitions apparently indicate 

 that the double condition arises as a longitudinal split 

 of a single original testis. This is quite different from 

 the normal origin of double testes in which they grow 

 apart as the.v form at the two poles of the genital primor- 

 dium. Heterodera ma)iovi is the only example with two 

 testes known in the Phasmidia. In Antieoma typiea, Cobb 

 1 890, described a form with parallel testes in tandem. 

 This arrangement (Fig. 124 L) may easily be considered 

 as due to a shift of the posterior testis from a normally 

 opposed to a tandem position. 



150 



