Steiner: Intersexes in Nematodes 

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151 



TAIL OF INTERSEXUAL FEMALE 



Figure 5. Two views of the tail of fe- 

 male Ag. decaudata, having a male sex open- 

 ing (o so). In the normal female no such 

 openings occurs, and this cannot be con- 

 sidered a rudimentary anal opening because 

 tliat region has been lost in the adult form 

 (sec Figure 4). It is difficult to arrange 

 intersexual characters in a very definite 

 graded series because in some cases one male 

 organ will be highly developed and in other 

 individuals this organ will be rudimentary 

 and others will be much more prominent, c, 

 sub-median longitudinal chord ; /, fat body ; 

 S so., male sex opening. 



with males. The intersexual state is 

 only to l)e determined by examination 

 of the tail end. This tail end has 

 more or less the structure and organi- 

 zation of the tail end of a male. We 

 have pictured such transformed female 

 tail ends in Figures 4 to S. All grades 

 of transformation can be seen from the 

 typical female to a typical male tail 

 end (Figure 2). 



Figure 4 is the tail end of a female 

 which shows only a small amount of 

 tissue (connected with the fat body) 

 which has to be regarded as tissue of 

 a male character, since in the normal 

 female no such structure exists. 



A more pronounced intersexuality is 

 developed in the female whose tail 

 end is sketched in Figure 5. Here 

 a rudimentary male sex opening is 

 present. It may be said that this 

 structure should be compared with an 

 anal opening and be designated as such. 

 The ancestors of Agamermis certainly 

 once had a complete alimentary tract, 

 and therefore also a functional anal 

 opening. The figured rudimentary 

 openings could be said to be a rudi- 

 mentary anal opening, homologous with 



MALE CHARACTERS MORE HIGHLY 

 DEVELOPED 



Figure 6. Tail ends of two females show- 

 ing more marked intersexuality. The indi- 

 vidual on the left has a male sex opening 

 ($ so) and male papillae (S ppl) . The 

 one on the right has two rudimentary spicula 

 {sp), and male papillae much less developed 

 than the other specimen. Irregularity in the 

 development of the male organs is charac- 

 teristic in these intersexes. It is believed 

 that this is due to the fact that these forms 

 are produced by hybridization' of different 

 races, in which the time and rate of differ- 

 entiation of the sex organs vary considerably. 



the anal openings of other female 

 nemas. but the ontogenetical develop- 

 ment of our forms precludes such a 

 possibility. As Cobb first observed, and 

 as described in the above-mentioned 

 preliminary paper", the young larva of 

 Ag. decaudata in entering the host 

 loses about five-sixths of its total body 

 length by self -amputation. What de- 

 velops into the adult Ag. decaudata is 

 only the small head part of the pre- 

 parasitic larva, shown in Figure 4. At 

 a point about one-sixth of the larva's 

 total length from its head end a small 

 series of coin-like cells develops, form- 

 ing a distinct node. In entering the 

 host the larva drops all of its body 

 posterior to this node by breaking ni 

 two at this point. Sometimes the pos- 

 terior part of the larval body does not 

 enter the host at all, l)reaking off as 

 soon as the head of the larva has 

 worked its way into the host. In other 

 cases the whole larva enters the host 



