470 ON THE ARTIFICIAL CULTURE OF MARINE PLANKTON ORGANISMS. 



integration. The Hask was not again examined niicroscopically nntil 

 July 25th of the following year (1907). No sign of the larva? could 

 then be seen, but the culture of Pleurococcus remained pure and 

 healthy. 



Subsequent experiments were made with spawn, which was deposited 

 by the females in confinement. Although the spavv"n hatched and gave 

 apparently healthy larvae, these did not live for more tlian a few days. 



Calanus finmarcliicus. A single experiment is perhaps worth re- 

 cording, as showing that it ouglit to be possible to rear this species 

 without great difficulty. On August 8th, 1905, to a rlask containing 

 1000 c.c. of outside water (unsterilized) there was added h c.c. of 

 Miquel's solution B and h c.c. of a 1*5 per cent solution of anhydrous 

 sodium carbonate. A few Calamis finmarcliicus and some decapod 

 Zoeas were put in, together with a quantity of a culture containing 

 mixed diatoms. On September 8th all the Zoeas were dead, but three 

 Calanus were alive, Siwdi Nltzschia and a number of bottom diatoms 

 were very plentiful. On September 17th the three large Calamis were 

 alive and vigorous, and a considerable number of NauiAii were seen in 

 the flask. By September 22nd two of the Navplii had developed into 

 voung Calamis. These, however, did not live for more than a week 

 or ten days, and the adults also died. The flask was abandoned on 

 November 13th, the water in it not having been changed since the 

 commencement of the experiment. 



Ecliinus hybrid. A successful experiment on crossing i,'. escv.kntvs 

 and E. aciitus was carried out by Mr. W. De Morgan, wiio v/as 

 working at the Plymouth Laboratory. We provided him with 

 treated water and diatom cultures for food, and lie followed our 

 methods. We are indebted to him for allowing us to publish these 

 results. Some eggs from a ripe K cscnlentus were fertilized by active 

 sperm from U. acutiis in sterilized water on March 29th, 1909. Healthy 

 larvDe were obtained and vv^ere transferred two days later to tank- 

 water, which had been treated with animal charcoal and filtered 

 through a Berkefeld filter. A culture of Nitzscliia closterium, var., was 

 added as food, and the larvic developed rapidly, feeding well. Several 

 were completely metamorphosed on May 7th, or thirty- nine days after 

 fertilization. In all thirty young hybrids were obtained, and a number 

 of these are still alive and feeding on red weeds. 



Sacculina carcini. Mr. Geoffrey Smith has recorded the fact (Quart. 

 Juurn. Micr. Sci, LI, 1907, p. 625) that he was able to rear the larvne 

 of Sacculina up to the Cypris stage, when they attaclied themselves to 



