ON A HERMAPHRODITE SPECIMEN OF AMPHIOXUS. 511 



observed to spawn during the day,* but it is probable that this spawning- 

 may have been abnormal and induced by the animal having jumped out 

 of a bowl and remained dry on the bench for a little while. 



In the second experiment in which fertilised eggs were obtained the 

 embryos had reached the blastula and gastrula stages by 1.0 p.m. At 

 6.0 p.m. on the same day, June 15th, the gastrulse began to elongate, 

 and by 9.0 p.m. t\\o to three mesoblastic somites were developed and the 

 larvae were beginning to find their way out of their fertilization membranes. 

 On June 16th at 2.5 p.m. the larvae had developed six to eight pairs 

 of mesoblastic somites and the head cavities. On the 17th at 2.30 p.m. 

 the larvae reached a stage similar to Hatschek's Fig. 64 ,f in which the 

 club-shaped gland is present. At Naples this stage is reached at an age 

 of about 36 hours, whereas the Plymouth embryos only reached the 

 corresponding stage at an age of about 60 hours. During subsequent 

 days the larvae increased a little in length and were observed to be feed- 

 ing, but even on the 30th of the month when the larvae were a fortnight 

 old only the first few gill-slits had appeared, and shortly afterwards it was 

 unfortunately necessary to abandon the larvae. 



In preserving batches of larvae it was observed that the individual of 

 the latter stages became stuck to the bottom of the vessel in the head 

 region. This circumstance seems to point to the possibility of the club- 

 shaped gland pouring out some secretion to the exterior, since this gland 

 is the only organ developed at this stage ; and since moreover, according 

 to Willey,{ " this stage of the larval development appears to be of the 

 nature of a resting phase, during which the larvae accumulates energy for 

 future growth," it may be that a secretion of the club-shaped gland 

 serves to attach the larva temporarily to objects during this resting stage, 

 or to suspend the larva in the water (see Willey, I.e., p. 130). These are, 

 however, merely suggestions, which nevertheless might well repay 

 further investigation by naturalists who may have the opportunitv of 

 doing so. 



It may further be noted that the opening of the club-shaped gland is 

 on the left side ; hence if a secretion of this gland is used for attaching 

 the larva temporarily to objects, then the larva would be able to feed onlr 

 from the right side of the body. As is well known, the first formed gill- 

 slits do develop on the right side of the body and afterwards shift over 



* The actual time was not recorded, but it was some time between 11 a.m. and 

 4.30 p.m. 



t B. Hatschek, " Entwicklung des Amphioxus," Arb. Zool. Inst. Wien., 1881, Vol. IV. 

 X A. Willoy, Amphioxus and (he Ancestry of the Vertebrates, 18C4, p. 172. 



