SECONDARY SEXUAL CHARACTERS OF CRAYFISHES. 22Q 



These aberrant females totalled about 1.5 per cent, of all the 

 females collected outside of Lake Deluvun. 



DISCUSSION. 



From the data cited above it is evident that the presence of 

 male second.tr>' -e\ual characters in females of Cambarus ririlis is 

 not uncommon in the waters of Wiscon>in. The exploration so 

 far ha- hi TII very limited but from the evidence already gained it 



rns quite probable that other localit ; e> may be found which 

 will c< .nt. tin a- large a proportion of aberrant female- as have been 

 found in Lake Delavan. It may be that >e\ interi;rade- in 

 ririlis may be much more common ^em-rally than i> 

 to I.e the case. 



-mall number of intersexes in Cani/xirns /m>/>/;/<//</<s and in 

 virilis outside of Lake Delavan make- it po iliU- to 

 approach tin- (juestion as to the possible cau-e- \r tin- inter-, 

 in an indirect and hypothetical way but the very lii^h proportion 

 of inlet -e\rs in Cambarus virilis found in Lake I U-lavan should 

 allipid a much more satisfactory basis for such a >tnd\. 



\lti-i observations and experiments upon intersexes in l-'iddlrr 

 1 bs l'i"ti^or Morgan 1 reviews the po>>ibli- causes t"i intcr- 



6S in Arthropods in general and more particularly in the 

 CniMacra. lie points out six possibilities. (l) Tin- ini> 

 ma> In- true hermaphrodites, possessing to some decree Imth 

 o\arie- and spermaries. (2) Parasitism altectiny, tlu- Im-t 

 directK may be responsible for the intersexes. (,^i rara>iti>m of 

 the vonaU ma\ cause a loss of the supposed control of the dr 

 tion of de\el<.pinent of the secondary sexual character^. (41 The 

 intersex -ondition may be due to some environmental inthu-ncr. 

 - Changes in genetic constitution may account for the condition. 

 (6) Peculiar or accidental embryonic development may be the 

 cause. 



Of the alio\e po-,-.ibilities the third and the fifth have been 

 considered in connection with intersexo in ('mnhanis f>rnf>in(]iins 

 in another p.ij" It w.ts borne in mind that the e\ idence 



1 Miv;.in. I . II., 1920, \merican Naturalist, Y<>1. 54. pi'- 820-246. 

 : Turn-i. < . I . nj-'j. : - on the Secondary S-xu.il i li.u Cr.iy- 



I. Male Secondary Sexual Characters in Femal' ;'rt>imiuus," 



BULLETIN, Vol. XL VI., Xo. 6. 



