18 



and rapid chemical to use. 



It may be well to mention the method of keeping Go - 

 nionema alive in the laboratory, Rimning water is not de- 

 sirable, and it is of no benefit to either medusae or lar- 

 vae to change the water frequently, as I learned after much 

 laborious effort to keep the specimens alive in this man- 

 ner. Balanced aquaria furnish the best environment for 

 these creatures. I succeeded in keeping a large number of 

 larvae in healthy growing condition for six months in aqua- 

 rium jars in the laboratory. The quantity of v/ater was 

 kept constant by adding fresh water to make up for evapora- 

 tion. Food was furnished in the form of various protozoans 

 and other microscopic organisms. Oxidation was secured by 

 means of large quantities of diatot.is which wore reared for 

 the purpose. Cultures were made from the scrapings of eel- 

 grass, etc., and the diatoms which accumulated from them, 

 collecting in cliomps on the bottom of the dish, were scrap- 

 ed into the water with the larvae. At the end of Janizary, 

 the polyps which came from eggs laid the preceding August, 

 died vfithoiit undergoing metamorphosis. Their death was 

 probably due to a lack of food supply sufficient for the re- 

 quirements of their growing bodies. 



D» Segmentation - The egg is spherical, averaging .07 mm. 



