424 j<:. J. Ai.i.KN AND j;. w. nelson. 



l)een made to rear the larvae of nudibrunchiate molluscs, but 

 up to the present not much success has been achieved. The 

 best experiment was one made with larvae of Archidoris 

 tuberculata. A number of veligers of this species hatched 

 out on May 8th, 3906, from some spawn whicli had just 

 been collected from the shore. Some of these were put in a 

 Hask containing 1000 c.c. of sterilised animal-charcoal water, 

 and about 1 c.c. of line plankton was added. On May 14tli 

 a few veligers were transferred to another tiask of sterilised 

 animal-charcoal water and some pure cultui-e of the green 

 alga, Pleurococcus mucosus, was added. AVhereas the 

 larvae in the original Hask did not live long, those provided 

 with the green alga fed well and developed for some con- 

 siderable time. A number of them were active and vi<rorous 

 on July 4th, i. e. fifty-one da^'^s after hatching, and several 

 were still swimming at the end of July. On August 15th 

 none could be seen moving, but two of those which lay on 

 the bottom, when examined with the microscope, showed no 

 sign of decomposition. The animal was retracted in the shell, 

 but the tissue looked healthy, and the eye-spots and otoliths 

 could be seen. The growth in the flask seemed to be a 

 quite pure culture of IMeurococcus. Larvas were examined 

 again on September 14th, and appeared much as in August, 

 the tissue still showinsf no sio"n of disiuteo-ration. The flask 

 was not again examined microscopically until July 2oth of 

 the following year (1907). No sign of the larvae could then 

 be seen, but the culture of Pleurococcus remained pure 

 and healthy. 



Subsequent experiments were made with spawn, whicli 

 was deposited by the females in confinement. Although the 

 spawn hatched and gave apparently healthy larvge, these did 

 not live for more than a few days. 



Calanus finma rchicn s. — A single experiment is perhaps 

 worth recording, as showing that it ought to be possible to 

 rear this species without great difficulty. On August 8th, 

 1905, to a flask containing 1000 c.c. of outside water 

 (unsterilised) there was added h c.c. of Miquel's solution B 



