SECONDARY SKXTAI. ( HARACTERS OF CRAYFISHES. 2~ I 



DISCUSSION. 



The occurrence of both male and female secondary sexual 

 characters in the same individual is so rare and sporadic that it 

 has seemed futile to speculate as to its cause. However, when 

 nineteen instances are found in a limited area within two year:- it 

 would seem that a close study of conditions might yield results. 

 Two possible explanation- -u^gest them-eh 



I. The gonad- may ha\v been damaged by parasites so that 

 the po~-ible control () f tin.- development of the -econdary sexual 

 character- would be lackiiu. 1 'arasites 2 were found, indeed, in 

 t number- in both male- and in female- and there can be no 

 doubt thai they did exten-i\e damage to the ti--ue- of tin- cr 

 fishes. ' Ovaries, ainu-mary canal-, ^reen -land- and 



li\er- wen- often heaxilv infe-ted and partially dc-troycd. The 

 seeming effe< i of p.u.i-iti-m of the gonads upon the development 

 of the -e< ondary -e\ual characters has been worked out in i^reat 

 <let. iil by Smith Pii" . This author fount number- . .f the 



spider i 'tab (Inachm so p.n-a-itized by Cirrepede Sacculina that 

 the ovaries and -pel in arie- . .f Inachlts were frequently de-tro\e.l. 

 The timlin^- wiih regard to the effect upon t ; mlary -exual 



characters and hi- . .mclu-ioiis may be found in the following 

 -tatemcnt : " \Ylicie.i- the malrs under the influence . .f the para- 

 site, wen ;>al'le . all the femai' ndar\ -exual 

 characters and under certain conditions mi^ht e\eii le\ elope 

 OVa in their testes, tin- infected female> on the other hand, 

 although the ovaries in some iinplei-l\- ili-ap|ie,[re.l, ne\-r 



approached t" the male primal^ or secondary -exual characters 

 in the slightest degree." ". . . Tliepi. nlinn can-ed 



\-omii; female- uiuler i.; mm. in carapace length to assume ; 



matureK llie adult t \ pe -f abiloineti and abdominal appemla. 

 ". . . it \\ould appear that the male wa- a potential herma- 

 phrodite and the female purely female." 



If the irreguluritk-- de-cribed j,, ('nmhtirits prof>in<]nns are due 

 to para-iti-m it mi-h.t be ex|u-cie<l that the number of irre-ulari- 

 tie- would IK- -omewhat j >ropor t ional to the number of heavily 

 para-iti/ed indi\ idual-. Thi-, ho\\e\er. does not pro\ e to b 

 the case for para-iti-m i- unite common and irregular secondary 

 sexual character- are rare Again, if para-iti-m can-es these 



