ON A HERMAPHRODITE SPECIMEN OF AMPHIOXUS. 509 



Langerhans stated* that he had detected the tails of spermatozoa 

 among young ovarian ova of Amphioxus, and recently in 1912 Goodrichf 

 described a more definitely hermaphrodite specimen from Naples which 

 closely resembles the one obtained here at Plymouth in having only one 

 gonadial pouch producing eggs — the ninth on the left side — but with the 

 remaining forty-nine pouches full of spermatozoa. 



Goodrich has already pointed out that hermaphroditism would appear 

 to be a rare phenomenon in Amphioxus since large numbers have been 

 and are being carefully examined. It occurred to me, however, that 

 possibly the hermaphroditism might be more common in Amphioxus 

 than would appear to be in the case, for after the discharge of the 

 gonadial products the gonadial pouches contract into a very small 

 compass, and presumably a fresh set of gonadial products are formed 

 subsequently. Thus it would be possible for a given individual Amphi- 

 oxus to have two different sets of gonads, first of one sex and afterwards 

 of the other. Moreover, such a change would probably not be detected 

 unless a number of Amphioxus were reared in captivity from the young 

 to the adult stage. In this way the chance observations referred to 

 above of two males each with one egg-bearing pouch may possibly 

 indicate an unsuspected change of sex in the life-history of the animal. 

 If such a change were to occur the occurrence of egg-bearing pouches in 

 a male might be an expression of a precocious development of female 

 characteristics. A further indication that a change of sex would be in 

 the direction of male to female lies in the fact that the hermaphrodite 

 forms are both of medium size : Goodrich's specimen being about 

 4*7 cms. long, and mine measured 44 cms. in cedar-wood oil. It is very 

 probable that the animals become mature for the first time at about 

 this size. 



On the view, however, that there is a sex-change in Amphioxus one 

 would expect all the young individuals to be of the same sex, but the 

 researches of three different investigators, namely, Legros (I.e.), Neidert 

 and Leiber, J and Zarnik,§ show that both male and female gonads have 

 been traced in very small individuals. Hence it seems certain that there 

 cannot be any total sex-change in Amphioxus ; but there still remains 



* P. Langerhans, Archiv f. Mih: Anat., Bd. XII, 1876, p. 326. 



t E. S. Goodrich, " A Case of Hermaphroditism in Amphioxus," Anat. Anz.. 42 Bd., 

 1912. 



J L. Neidert u. A. Lciber, " Uber Bau und Entwickhmg der Weiblichen Geschlechts- 

 organe des Amphioxus," Zool. Jahrb., Bd. XVIII, 1903. 



§ B. Zarnik, " Uber die Geschlechtsorgane von Amphioxus," Zool. Jahrb. Abt. Anat., 

 Bd. XXI, 1905. 



