510 J. H. OKTON. 



the possible, but hardly probable, occurrence of a sex-change in only 

 some individuals. 



It would therefore appear that these occasional hermaphrodites in 

 Amphioxus must remain for the present unexplained like the similar 

 and not uncommon phenomena among many fishes.* The abnormahty 

 of the liver and the intestine as well as that of the sexual organs points, 

 however, to some deep-seated disorganisation in the economy of the 

 animal, the cause of which I have not been able to detect. 



NOTES ON EXPEKIMENTS ON BEARING AMPHIOXUS. 



A few experiments were carried out this summer with the object of 

 obtaining the larvae of Amphioxus. As two of the experiments were 

 successful, and as the larvse of Amphioxus have apparently not been 

 obtained at Plymouth before, these notes may be useful to future 

 workers. 



Larvae of Amphioxus were obtained on two occasions on June 10th 

 and June 15th by merely isolating a number of adult males and females 

 in a small glass bowl. The adult specimens were examined under a 

 microscope when brought in and a few mature males put into bowls in 

 company with mature females. It is possible to distinguish the adult 

 sexes in the living condition, and indeed the hermaphrodite specimen 

 described in the preceding pages was identified as such while alive. 

 It was found advantageous to feed the Amphioxus on a fairly thick 

 culture of the diatom Nitzschia which the animals ingest in great 

 numbers. By gorging themselves with this food the Amphioxus are 

 probably able to extrude eggs or sperm more easily than when they are 

 empty. 



Spawning apparently occurs usually overnight, as gastrulse were 

 cbtained in both experiments about midday. It is not easy to calculate 

 the time of spawning from the known age of gastrulse reared at Naples, 

 since the rate of development of larv« at Plymouth is undoubtedly 

 slower than at Naples, as was shown by subsequent observations. Since, 

 however, gastrulse were obtained about noon it seems likely that spawn- 

 ing had occurred sometime about midnight. In this respect it is interest- 

 ing to observe that the hermaphrodite specimen just described was 



* With regard to the occasional hermaphrodites among fishes it may be remarked 

 that it is highly important to know the size and also the age of specimens — which are 

 usually omitted from descriptions — if the data are to be useful for investigating 

 the life-history of the fish. 



