RELATING TO SECONDARY SEXUAL CHARACTERS. 89 



the female. The black lower corner of the tail in the male is not 

 changed by castration. 



When the skin along the middle line of the back of the female is 

 transplanted upon the back of a normal male (in place of his own comb) 

 the transplanted tissue develops into a comb. In other words, under 

 the influence of the testis, the dorsal mid-line tissues of the female 

 change into those characteristic of the male. When pieces of skin of 

 a male with the white tail stripes are grafted on the side of the tail of 

 another male, the stripe remains, but when grafted similarly on a 

 female the stripe slowly disappears. The result shows that its presence 

 depends on the testis. 



A remarkably clear case of hermaphroditism in amphibians was 

 found by V. la Vallette St. George. He found an individual of Triton 

 tceniatus that was outwardly a male with well-formed dorsal comb. 

 In the interior were two large testes in normal position and just 

 lateral to these on each side a large ovary. Sections showed ripe sperm 

 in the testes and typical ova in the ovary. Sperm-ducts were present, 

 but no oviducts. The presence of the testes will, of course, account for 

 the development of the secondary sexual characters of the male. 



Other cases amongst the Anura have been recorded by Loisel and by 

 Marshall, Spengel, and Knappe. In the early stages of the gonad in 

 frogs there appears to be an hermaphroditic stage in which egg mother- 

 cells and sperm mother-cells are both present, at least in those individ- 

 uals that will later become males (Kusakowitsch) . 



The normal hermaphroditism of certain fish (Serranus) and its rare 

 occurrence in other species (recorded by Shattuck and Seligmann) 

 need not be recorded here. 1 



D. EVIDENCE FROM CRUSTACEANS. 



In the Crustacea the secondary sexual characters are not marked, 

 except in a few cases. In the amphipods, Holmes has shown direct 

 contact plays the chief role in mating, and in the crayfish it has been 

 shown by Dearborn, Andrews, and Pearse that sex recognition is largely 

 tactile. Chidester also has shown this in crayfish. Even in crabs, 

 and especially those living on land which have well-developed eyes and 

 good vision, secondary sexual differences are as a rule slight and the 

 mating instincts simple. On the other hand, the enormous chela of the 

 male of the fiddler is supposed to be a secondary sexual difference 

 (mainly because no other use for it has been found). Pearse suggests 

 that the waving of this claw by the male is used as a sex signal, although 

 he is disinclined to accept Alcock's view that it has become "con- 

 spicuous and beautiful in order to attract the female." 



The most remarkable case known of a change in the secondary- 

 sexual characters of one sex into those of the other was discovered by 



1 See the latter also for references to Lacertilia and Chelonia. 



