THE ORIGIN OF GYNANDROMORPHS. 99 



tionally. They believe that any one individual after passing through 

 this stage becomes definitely either male or female, although certain 

 individuals remain sterile, neither alternative being realized (quoted 

 from Caullery, Les Problemes de la Sexuality, 1913, p. 53.) 



A gynandromorph was described in 1914 by Vayssiere and Quintaret 

 in one of the sharks, Scyllium stellare. The left pelvic fin was female, 

 the right male with a well-developed clasper. An ovary and both ovi- 

 ducts were present. On the right side there was a testis, with normal 

 male ducts on this side only. 



Miss Ruth C. Bamber described (1918) a hermaphroditic shark, 

 Scythum cavicula, in which both testes were present. The anterior 

 end of the right testis had ovarian tissue. Normal oviducts were 

 present and the male ducts were well developed. Externally this 

 animal was typically a male with well-developed claspers. 



Most of the bony fishes have separate sexes, but certain species 

 (Serranus) are true hermaphrodites. (See Shattuck and Seligmann.) 

 Other species give exceptional individuals that have traces of both 

 sexes. Chidester has described a male fundulus with ova attached 

 to the mesentery of the intestine and liver. 



GYNANDROMORPHS IN AMPHIBIA. 



The sharp separation into adult males and females is characteristic 

 of the group Amphibia. According to Miss Stevens there is a pair 

 of XY chromosomes in the male of one of the urodeles, but in a frog, 

 Rana pipiens, Swingle states there is only one sex chromosome in 

 the male. Certain species of frogs pass through a stage that appears 

 to be hermaphroditic — at least individuals that later become males 

 may contain in the young tadpole stage large cells that appear to be 

 incipient ova, which later disappear when the spermatozoa are formed. 

 In the adult toad there is a region anterior to the testis proper called 

 Bidder's organ, in which ova-like cells are present. There are a 

 number of observations in the older Uterature to the effect that well- 

 fed tadpoles produce more females than males, and lice versa, that 

 starved tadpoles give an excess of males. On the other hand, there 

 are other later observations that flatly contradict these conclusions. 

 There are some observations, especially those of King, that show the 

 proportion of males and of females may be determined by treating the 

 eggs (or even the sperm) with certain substances in solution, but 

 whether the change is due to the chemicals injuring one kind of sperm 

 (or of egg) more than the other kind, or whether the change is of a 

 kind to really determine the sex, irrespective of the combinations 

 formed by the germ-cells, is open to debate. The most remarkable 

 observations on Amphibia are those of Richard Hertwig and his pupils, 

 particularly Kuschakowitsch. They show that by delaying the 

 fertilization of the egg there is caused an increase in the number of 



