ITS BREVITY OF LIFE. • 89 



medusoids. And this explains the very great abun- 

 dance of the httle airy creatures that presently swarm 

 in the vessel in which we have put only a limited 

 colony of the zoophytes. 



As the embryo was slowly emerging from the nar- 

 row neck of the vesicle, I could see the fluids run 

 into those parts of the tentacles that were extruded, 

 carrying minute clear granules into them. 



The medusoid w^hen liberated seemed feeble, its ten- 

 tacles corrugated and shortened; it slowly fell through 

 the water, making now and then a w^eak contraction, 

 but it gathered strength in a few seconds, the tentacles 

 lengthened, and the motions acquired the vigour and 

 sprightliness that characterize this interesting form. 



Again I have been utterly unable to preserve the 

 fi'agile medusoids for more than a few hours, though 

 with every precaution to maintain the oxygenation of 

 the water by living algce. They soon sink to the 

 bottom, when the tentacles become indistinct, the 

 whole outline becomes obsolescent, and shortly a mere 

 mass of granules is all that remains. Has it ever 

 been proved that these continue the race ? Are they 

 male polypes ? 



The Laomedea genicnlata does not always grow in 

 the close forest-like masses above described. I found 

 in May a frond of Laminaria digitata, just ready to 

 throw off the old lamina of last season. On the smooth 

 olive expansion of this old frond the gemmule of a 

 Laomedea had rested after its brief gyrations ; from 

 it a glassy thread of extreme tenuity had crept along 

 for a length of about seven inches, adhering so 

 firmly to its support as not to be removed without 



