Mr Gray, True and apparent hermaphroditism in sea-urchins 481 



Note on true and apparent hermaphroditism in sea-urchins. By 

 J. Gray, M.A., Balfour Student, Cambridge University. 

 [Read 16 May 1921.] 



During the winter of 1913 I had occasion to examine at Naples 

 the gonads of a large number of specimens of the sea-urchin 

 Arbacia pustulosa. It is exceedingly easy to distinguish the two 

 sexes of this animal; the eggs and ovarian tissue of the female 

 contain a dark Ted pigment, whereas the testes of the male are 

 devoid of any pigment. The gonad of the female is brick-red in 

 colour from the very early stages of its development. That of the 

 male is yellowish white. 



On opening one individual, a unique condition of the gonads 

 was observed: four of the gonads were apparently female — 

 being of the usual colour, and of considerable size. Part of the 

 fifth gonad was also in the same condition, but the majority of 

 the gland was typically male in appearance. On examining this 

 portion of the abnormal gland, spermatozoa were found, which, 

 though normal in appearance, were either motionless or only 

 capable of feeble movement. 



On sectioning the whole of the gonads, I was most surprised 

 to find no trace of ova or ovarian tissue. On the other hand, those 

 parts of the gonads which were female in appearance were found 

 to be full of a mass of degenerating spermatogonial cells, which 

 failed to take up any of the usual stains. The walls of the gonad 

 were perfectly normal. 



This animal is of interest as it would appear that a derange- 

 ment of the sex-cells has been attended by an inversion of the 

 secondary sexual characters. Although no parasite was observed, 

 the condition of the gonad recalls the well-known effects of para- 

 sitic castration in the Crustacea. If this view is correct, the male 

 of Arbacia appears to be heterozygous for sex. 



Owing to the courtesy of Mr H. M. Fox, I have been able to 

 examine the gonads of a true case of hermaphroditism in the urchin 

 Strongylocentrotus lividus. In this case three of the gonads were 

 completely female, while the other two contained both ripe eggs and 

 spermatozoa, which were fertile inter se. In one of the abnormal 

 gonads most of the tubules were female. It appears that this 

 animal was essentially a female— possibly an "intersex." No 

 abnormality was found in either the male or female portions of 

 the gonads. 



As far as I am aware the only other description of an hermaphro- 

 dite sea-urchin is that given by Gadd* of an individual of Strongylo- 

 centrotus droebachiensii, in which one gonad was male and the 

 remaining four female, 



* Zool. Anz. vol. xsxi, 1906-07, p, 635. 



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