Steiner: Intersexes in Nematodes 



149 



fiii > g^- °Ji2 



TAIL END OF MALE AND FEMALE 

 NEMATODES 



Figure 2. Intersexes are individuals hav- 

 ing the reproductive organs of one sex and, 

 in addition, certain organs or tissues typical 

 of the other. All of the intersexes so far 

 observed in nematodes have been females in 

 which certain typically male parts are pres- 

 ent. Above is shown the tail end of a nor- 

 mal female (right) and of a normal male 

 (left), showing the male organs that are 

 found in intersexual females (Figures 5-8). 

 dct ej, ejaculatory duct ; brs viusc, bursal 

 muscle ; $ ppl, male papilla ; ptrct msc, pro- 

 tractor muscle ; rirct msc, retractor muscle ; 

 sp, spiculum. 



as 1854 three intersexual females and 

 is very much puzzled over this unusual 

 combination of male and female char- 

 acters. 



The majority of the specimens of 

 Agamcrmis dccaudata which I have 

 had the opportunity to study came 

 from Falls Church, Virginia, and were 

 collected by Mr. J. R. Christie. It 

 was very striking that the specimens 

 with intersexual characters were as 

 numerous as, or even more numerous 

 than, normal females. 



One important fact, to be noted at 

 the outset, is that hitherto only inter- 

 sexual females have been observed, — 

 that is, all specimens with intersexual 

 characters were females ; the female 



A SLIGHTLY INTERSEXUAL FORM 



Figure 3. Tail end of female Ag. dccau- 

 data, showing a small amount of male tissue 

 { $ t). Goldschmidt experimentally pro- 

 duced "consecutive intersexuality" in moths 

 by crossing related races. These individuals 

 would begin life as females and gradually 

 change to males, at the same time losing 

 their female characters. He accounted for 

 this change by assuming that the sex de- 

 terminers of the different races used in the 

 experiment had a different relative rate of 

 activity, and that an initially slow-working 

 "male factor" would gradually increase in 

 activity until it overshadowed the "female 

 factor," when the individual would change 

 from a female to a male. 



sex organs were completely and nor- 

 mally developed. Vulva, vagina, uteri 

 and ovaries were normal and in most 

 of the animals eggs were present in 

 the oviducts and uteri. Up to the 

 present the writer has never seen a 

 male with intersexual characters, and, 

 as far as he knows, no other investi- 

 gator has. 



Let us now first see what a normal 

 female and male of this species look 

 like : 



The two sexes may be distinguished 

 from each other with the naked eye, 

 as they are in most cases distinctly 

 different in size. The photographs, 

 (Frontispiece), show a female and 

 several males that were found together 

 in the soil. The female is several 

 times larger than the male. The aver- 

 age length of six females was found 

 to be 393.7 mm., ranging from 190 

 to 380 mm., whereas the average length 

 of ten males was only 63.5 mm., rang- 



